Sostenuto dalla DA034783 NIH / NIDA. Ringraziamo Bryan A. Killinger per l&#39;assistenza tecnica con il multimero-PAGE.

1. Preparazione del tessuto <ol><li> Preparare 10 ml di 4x tampone campione BN-PAGE (200 mM Bis (2-idrossietil) ammino-tris (idrossimetil) metano (Bis-Tris), 200 mM NaCl, 40% w / v di glicerolo, 0,004% Ponceau S, pH 7,2 ). NOTA: Questa soluzione madre può essere effettuato in anticipo e conservato a 4 ° C. </li><li> Diluire 250 ml di tampone campione 4x in 750 microlitri dH 2 O contenente 1x commerciale cocktail di inibitori delle proteasi. Vortex e freddo sul ghiaccio. </li><li> Omogeneizzare 20 mg di tessuto bersaglio nel tampone campione BN-PAGE 1 mL 1x ghiacciata con 30 colpi di un omogeneizzatore Dounce pulito. Nota: per questo esperimento di dimostrazione, il tessuto bersaglio è tutto il tessuto del cervello di ratto. Dopo omogeneizzazione, i campioni possono essere trattati con detergente delicato come 2% digitonina di solubilizzare e permettere elettroforesi delle proteine ​​di membrana. </li><li> Trasferire l&#39;omogeneizzato in una provetta da microcentrifuga da 1,5, e centrifugare a 14000 xg per 30 min a pellet contenuto cellulare insolubili. afteR centrifugazione, decantare il surnatante in una provetta pulita sul ghiaccio. </li><li> Seguire le istruzioni del produttore per misurare la concentrazione di proteine ​​surnatante utilizzando acido bicinconinico (BCA) o simile saggio delle proteine ​​quantificazione. </li><li> Se il campione omogenato (s) contengono detersivo, aggiungere una quantità di 5% Coomassie Blu G-250 in soluzione acquosa sufficiente a portare la soluzione omogenato al 0,25% Coomassie. </li></ol> 2. BN-PAGE <ol><li> Diluire 25 mL 20x nativo blu (BN) elettroforesi scorta (1,0 M Bis-Tris, 1.0 M tricina, pH 6,8) in 475 ml di dH 2 O contenente 0,002% Coomassie Blu per ottenere 500 ml di 1x tampone di corsa. <ol><li> Se i campioni contengono detersivo, anziché fare 250 mL di tampone di corsa 1x contenente 0,02% di Coomassie e altri 250 mL contenenti nessuno. </li></ol></li><li> tampone freddo (s) a 4 ° C. </li><li> Pulire e assemblare un gel di poliacrilammide versando cassetta secondo le istruzioni del produttore. </li><li&gt; Pour BN gel di poliacrilammide (3% strato T impilabili, 6% T risolvere strato) secondo una ricetta standard 7, e posizionare il pettine pozzo. </li><li> Dopo i gel sono polimerizzati, sciacquare la cassetta con dH 2 O e montare l&#39;apparecchiatura elettroforesi secondo le istruzioni del produttore. </li><li> Rimuovere il pettine bene e riempire i pozzetti con 1x tampone di corsa BN-PAGE. Evitare di riempire l&#39;intera camera interna con buffer finché i campioni vengono caricati. <ol><li> Se i campioni contengono detersivo, riempire i pozzetti con il tampone contenente 0,02% Coomassie Blu. NOTA: Eseguire le operazioni da 2,7-2,9 a 4 ° C. </li></ol></li><li> Utilizzando punte gel-caricamento, pipetta un volume di omogenato contenente 20 ug di proteine ​​nei pozzetti desiderati. Pipettare un volume equivalente di 1x tampone campione BN-PAGE in nessuna pozzetti inutilizzati. NOTA: Utilizzare la concentrazione di proteine ​​determinata dal saggio BCA per calcolare il volume appropriato di omogeneizzato da aggiungere allai pozzi. </li><li> Dopo che i campioni sono caricati, riempire la camera interna con 1x tampone BN-PAGE esecuzione. Assicurarsi che il gel è interamente immerso in un tampone. Successivamente, riempire la camera esterna con 1x tampone esecuzione al livello indicato dal costruttore. <ol><li> Se i campioni contengono detersivo, riempire la camera interna con il tampone 1x contenente 0,02% di Coomassie Blu, e la camera esterna con 1x esente da colorante tampone di corsa. </li></ol></li><li> Collegare gli elettrodi per l&#39;alimentazione, e elettroforesi le proteine ​​nel gel a 150 V finché la banda colorante progredisce ~ 2 centimetri in risolvere strato. Stop e scollegare l&#39;alimentazione. </li></ol> 3. Cross-linking NOTA: Eseguire i passaggi 3,1-3,6 a 4 ° C. <ol><li> Smontare l&#39;apparecchio di elettroforesi, e separare i vetri della cassetta gel. Rimuovere ed eliminare lo strato di sovrapposizione. </li><li> Accuratamente tagliare il gel appena sotto il bordo inferiore del fronte del colorante. PrendereCura di rendere questo taglio il più possibile liscio e diretto e quindi scartare il pezzo inutilizzato di gel. Questo lascerà una striscia di gel di poliacrilamide largo ~ 2 cm, che contiene tutte le proteine ​​del campione omogeneo. </li><li> Tagliare le parti inutilizzate lungo i bordi della striscia di gel. </li><li> Collocare con cura la striscia in 10 ml di soluzione salina fosfata tamponata (PBS) in un piccolo contenitore e mescolare delicatamente con la nutrimento per 30 minuti per equilibrare. </li><li> Dopo aver equilibrato, scartare e sostituire il PBS con altri 10 mL. Pipettare 500 μl di 25 mM DSP sciolto in dimetilsolfossido nel PBS e continuare a miscelare come sopra (fase 3.4) per 30 min. </li><li> Versare la soluzione DSP. Aggiungere 10 mL di cloruro di tris (idrossimetil) aminometano (Tris-HCl) di 0,375 M, pH 8,8, contenente 2% di sodio dodecil solfato (SDS) per staccare il DSP non reagito. Continuare la nutrazione per 15 minuti. </li></ol> 4. SDS-PAGE <ol><li> Mentre la striscia di gel sta spegnendo, preparare SDS-PASoluzioni gel GE secondo metodi standard 9. Non aggiungere i reagenti di polimerizzazione. </li><li> Dopo lo spegnimento, restituire la striscia gel ΒΝ a temperatura ambiente, e gettato la striscia in una nuova cassetta gel. <ol><li> Per fare questo, con attenzione raccogliere il gel e posizionarlo su un gel cassette piastra distanziale pulita. </li><li> Orientare la striscia in modo che la parte inferiore del fronte del colorante è più vicino all&#39;inizio della nuova cassetta (cioè, il lato che ha viaggiato lontano durante BN-PAGE dovrebbe essere più vicino alla parte superiore della nuova cassetta, il nastro gel deve essere ruotato dalla sua prima orientamento). Vedi Figura 3. </li><li> Posizionare la striscia in modo tale che il suo bordo superiore si trova anche con cui il bordo superiore della piastra di copertura sarà (cioè, sarà in cima nuovo gel). Assicurarsi che il fronte del colorante è parallela ai bordi orizzontali della lastra di vetro. </li><li> Spingere un lato della striscia asportato contro una delle pareti distanziatori, lasciando spazio su tegli dall&#39;altro per gel da versare e ad una normale proteina o scala da caricare. </li><li> Se il bordo inferiore della striscia gel contiene le aree irregolari Di, tagliarli accuratamente via. Se presenti, si intrappola le bolle durante gel colata. </li><li> Una volta che la striscia gel è posizionata correttamente, fissare la piastra di copertura sulla piastra distanziale. Applicare una leggera pressione per far uscire eventuali bolle d&#39;aria intrappolate. </li><li> Continuare a montare l&#39;apparato gel versare secondo le istruzioni del produttore. </li></ol></li><li> Aggiungere i reagenti di polimerizzazione al buffer di gel risolvere, e versarlo nella cassetta di gel preparata, con una pipetta sierologica. Riempire la cassetta gel per ~ 2 cm sotto la striscia di gel BN-PAGE asportato, per lasciare spazio per la sovrapposizione dei livelli. </li><li> Aggiungere 100 microlitri butanolo sopra la parte superiore del gel versato, e consentire 30 minuti per la polimerizzazione dello strato risolvere. Eliminare il butanolo. </li><li> Aggiungere reagenti di polimerizzazione alla soluzione di gel di impilamento. Utilizzando un serologpipetta ical, versare lo strato di sovrapposizione ad occupare tutto lo spazio vuoto rimanente nella cassetta gel. <ol><li> Inclinare la cassetta gel come lo strato di sovrapposizione viene versato in modo da riempire lo spazio sotto la striscia di gel, e le bolle d&#39;aria non sono intrappolati. </li><li> Come tampone di gel di impilamento riempie lo spazio vuoto al di sotto della striscia di gel, gradualmente restituire la cassetta gel a livello piede. </li><li> Continuare a riempire lo spazio vuoto accanto alla striscia gel asportato con il tampone di gel di impilamento, fino quasi overflow. </li></ol></li><li> Lasciare che la sovrapposizione dei livelli di polimerizzare per 30 min. NOTA: Fare 10x SDS-PAGE tampone di corsa (250 mM tris (idrossimetil) amminometano (tris), 1,9 M glicina, 1% SDS), mentre il gel è polimerizza. Questo può anche essere fatto in anticipo e conservato a temperatura ambiente. </li><li> Diluire 50 mL 10X SDS-PAGE tampone esecuzione stock in 450 mL dH 2 O per rendere tampone di lavoro 1x. </li><li> Dopo che lo strato di sovrapposizione è polimerizzato, rimuovere la cassetta gel dalla colataApparecchiatura, lavare con dH 2 O, e montare l&#39;apparecchiatura elettroforesi secondo le istruzioni del produttore. </li><li> Riempire la camera interna completamente con tampone di corsa SDS-PAGE 1x, quindi riempire la camera esterna al livello indicato dal costruttore. </li><li> Caricare spazio accanto alla striscia gel escisse con una scala peso molecolare o standard proteina appropriata. </li><li> Collegare gli elettrodi per l&#39;alimentazione, e elettroforesi i campioni a 120 V. Quando il colorante Coomassie corre il gel, arrestare e scollegare l&#39;alimentazione. </li><li> Analizzare il gel usando metodi standard di elettroblotting e rilevazione proteica legandosi 10 anticorpo. </li></ol>

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Gli autori non hanno nulla da rivelare.

interazioni proteina-proteina sono importanti per ogni compito esseri viventi svolgono. A causa di questo, sono oggetto di intenso scrutinio e di ricerca. Multimero-PAGE è un nuovo metodo per l&#39;acquisizione, la separazione e l&#39;analisi di un&#39;ampia gamma di complessi proteici. Abbiamo precedentemente dimostrato la sua applicabilità a studiare oligimerization della malattia associata proteina α-sinucleina 11. Tuttavia, è estendibile a molti complessi proteici, come mostrato nella <st...

<html> Funzione cellulare normale dipende da interazioni proteina-proteina 1, 2. Come risultato, malattie umane sono spesso caratterizzate da perturbazioni nel montaggio e il comportamento di vari complessi proteici 3. La capacità di caratterizzare tali interazioni è quindi cruciale. attuali mezzi di rilevamento di queste interazioni richiedono purificazione di proteine ​​target, spesso seguite da discesa dei loro partner interagenti. Purificazione convenzionale viene realizzata mediante centrifugazione differenziale, precipitazione e / o cromatografia 4. Questi metodi richiedono tempo, devono essere modificati per ogni proteina bersaglio, e spesso sfociano in basse rese. I moderni metodi di purificazione comporta la fusione di tag peptidici di proteine bersaglio, seguita da immunoprecipitazione o estrazione su colonne carichi di perline legati ad una molecola di cattura 5,&quot;&gt; 6. Mentre questo è estensibile per molte proteine, richiede sequenza modificazione del bersaglio, causando un potenziale costrutti che differiscono affinità per loro soliti partner di legame. La delicatezza di alcune interazioni proteina-proteina significa che questo metodo non può essere applicabile per molti scenari. Inoltre, i saggi di pull-down utilizzati per mappare le interazioni proteina-proteina possono non catturare un quadro preciso cellulari, a causa di gradi di libertà e limitato i livelli di non-native della proteina esca. Idealmente, complessi proteici possono essere rilevati nei loro stati native, senza la necessità di depurazione o di pull-down. Blu nativo elettroforesi su gel di poliacrilammide (BN-PAGE) è stato sviluppato come meno denaturante alternativa sodio dodecil solfato elettroforesi su gel di poliacrilammide (SDS-PAGE), e consente la separazione di alcune proteine e complessi da campioni biologici 7. Tuttavia, le proteine ​​in BN-PAGE separate basate su una larnumero ge di variabili, tra cui le dimensioni, carica, struttura tridimensionale, e associazione con altre molecole. Le interazioni di questi fattori causano spesso co-separazione delle proteine, formazione di aggregati, e scarsa risoluzione banda proteica. Elettroforesi bidimensionale nativo-poliacrilammide risolve alcuni, ma non tutti, questi problemi 8. Per aggirare le complicazioni associate con separazione nativo, alcuni autori utilizzano reagenti ammina reattiva reticolanti, come ditiobis (propionato succinimmidil) (DSP), per catturare complessi proteici in lisati di tessuto 4. Questi lisati trattati possono essere denaturate e separate mediante SDS-PAGE, preservando la dimensione originale e il trucco complessi proteici. Tuttavia, poiché i reagenti reticolazione reagiscono in base alla vicinanza di una molecola a un&#39;altra, e le proteine ​​nei lisati tissutali avere molti gradi di libertà e può stocasticamente interagire fondo non specifica croceIl legame può essere elevato, soprattutto nei campioni concentrati. Ciò può portare a risultati difficili da interpretare. Qui dimostriamo l&#39;utilizzo di un metodo ibrido BN-PAGE / SDS-PAGE, denominato elettroforesi multimer-poliacrilammide (multimer-PAGE), per separare e rilevare gruppi di proteine ​​in miscele complesse. Inizialmente, il lisato cellulare viene sospeso in gel di poliacrilamide tramite BN-PAGE. Il gel contenente lisato viene quindi reagito con il reagente di reticolazione DSP. Pseudo-immobilizzato e leggermente separato sul gel, le proteine ​​sono molto meno probabilità di reagire in modo non specifico, il che significa che la reattività di cross-linker di sfondo è ridotta. Dopo la reticolazione, le bande di gel vengono escise e separate mediante SDS-PAGE. Il gel risultante può quindi essere analizzato con qualsiasi mezzo tipicamente associato all&#39;elettroforesi del gel di poliacrilammide. Questo metodo consente la separazione e la rilevazione di complessi proteici nativi in ​​lisato tissutale non modificato, senza la necessità di ulteriori purificazione o tiraturan.

<table border="0" cellpadding="0" cellspacing="0" width="817">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Chemicals</td>
			<td style="width:195px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">&#949;-Aminocaproic acid</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">A2504</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Acrylamide</td>
			<td style="width:195px;">Acros Organics</td>
			<td style="width:119px;">164855000</td>
			<td>Toxic.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:336px;">Acrylamide/bisacrilamide 37.5:1 (40%T stock solution)</td>
			<td style="width:195px;">BioRad</td>
			<td style="width:119px;">161-0148</td>
			<td>Toxic.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Ammonium persulfate</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">A3678</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Anti rabbit IgG-HRP from goat</td>
			<td style="width:195px;">Santa Cruz Biotechnology</td>
			<td style="width:119px;">sc-2004</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Bicinchoninic acid assay kit</td>
			<td style="width:195px;">Thermofisher</td>
			<td style="width:119px;">23225</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Bis-tris</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">B9754</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Bovine serum albumin</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">A9647</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Butanol</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td style="width:119px;">A399-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Chemiluminescence substrate kit</td>
			<td style="width:195px;">ThermoFisher</td>
			<td style="width:119px;">24078</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Coomassie blue G-250</td>
			<td style="width:195px;">Sigma-Aldrich</td>
			<td style="width:119px;">B0770</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Digitonin</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">D141</td>
			<td>Toxic.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Dimethyl sulfoxide</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td style="width:119px;">D128-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Dithiobis(succinimidylpropionate)</td>
			<td style="width:195px;">Thermo Scientific</td>
			<td style="width:119px;">22585</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Dry nonfat milk</td>
			<td style="width:195px;">LabScientific</td>
			<td style="width:119px;">M0841</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Glycerol</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">G9012</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Glycine</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td style="width:119px;">BP381-5</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Halt Protease Inhibitor Cocktail</td>
			<td style="width:195px;">Thermofisher</td>
			<td>78430</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Hydrochloric acid</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td style="width:119px;">A144SI-212</td>
			<td>For titration. Caustic.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Methanol</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td style="width:119px;">A412-4</td>
			<td>For PVDF membrane activation. Toxic.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Monoclonal anti &#945;-synuclein IgG from rabbit</td>
			<td style="width:195px;">Santa Cruz Biotechnology</td>
			<td style="width:119px;">sc-7011-R</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">N,N,N&#39;,N&#39;-tetramethylethylenediamine</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">T9281</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">N,N&#39;-methylenebisacrylamide</td>
			<td style="width:195px;">Acros Organics</td>
			<td style="width:119px;">16479</td>
			<td>Toxic.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">NP40</td>
			<td style="width:195px;">Boston Bioproducts</td>
			<td style="width:119px;">P-872</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Polysorbate 20 (tween-20)</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td style="width:119px;">BP337-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Polyvinylidene fluoride transfer membranes</td>
			<td style="width:195px;">Thermo Scientific</td>
			<td style="width:119px;">88518</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Ponceau S</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">P3504</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Potassium chloride</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td style="width:119px;">P217-3</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Potassium phosphate monobasic</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">P9791</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Protease inhibitor cocktail</td>
			<td style="width:195px;">Thermo Scientific</td>
			<td style="width:119px;">88265</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">SDS solution (10% w/v)</td>
			<td style="width:195px;">BioRad</td>
			<td style="width:119px;">161-0416</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Sodium chloride</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td style="width:119px;">BP358-212</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Sodium dodecyl sulfate</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">L37771</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Sodium phosphate monobasic</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td style="width:119px;">BP329-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Tricine</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">T0377</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Tris base</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td style="width:119px;">BP152-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Tris-HCl (0.5 M buffer, pH 6.8)</td>
			<td style="width:195px;">BioRad</td>
			<td style="width:119px;">161-0799</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Tris-HCl (1.5 M buffer, pH 8.8)</td>
			<td style="width:195px;">BioRad</td>
			<td style="width:119px;">161-0798</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Name</td>
			<td style="width:195px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Instruments</td>
			<td style="width:195px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">GE Imagequant LAS 4000</td>
			<td style="width:195px;">GE Healthcare</td>
			<td style="width:119px;">28-9558-10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">ImageJ software</td>
			<td style="width:195px;">NIH</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Synergy H1 microplate reader</td>
			<td style="width:195px;">BioTek</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Gel Former + Stand</td>
			<td style="width:195px;">Biorad</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Microfuge 22R centrifuge</td>
			<td style="width:195px;">Beckman Coulter</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">2 mL dounce homogenizer</td>
			<td style="width:195px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Vortex mixer</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:336px;">Ultrasonic tissue homogenizer</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td style="width:119px;">FB120220</td>
			<td></td>
		</tr>
	</tbody>
</table>

multimer-page: a method for capturing and resolving protein complexes in biological samples

Ci sono molti metodi ben sviluppati per purificare e studiare singole proteine ​​e peptidi. Tuttavia, la maggior parte delle funzioni cellulari sono svolte da reti di interazione complessi proteici, che sono spesso difficili da studiare perché il loro legame non covalente e facilmente perturbato da tecniche di purificazione. Questo lavoro descrive un metodo per stabilizzare e separare complessi proteici nativi da tessuto non modificato usando elettroforesi bidimensionale poliacrilammide. Tessuto lisato viene caricato su un gel di poliacrilammide-blu nativa non denaturante, quindi una corrente elettrica viene applicata fino a quando la proteina migra a breve distanza nel gel. La striscia gel contenente la proteina migrato viene poi asportato e incubato con le ditiobis ammina reattiva reticolanti reagenti (succinimidil propionato), che stabilizza covalentemente complessi proteici. La striscia gel contenente complessi reticolati viene poi gettato in un gel di poliacrilammide sodio dodecil solfato, e tegli complessi sono separati completamente. Il metodo si basa su tecniche e materiali noti alla maggior parte dei biologi molecolari, che significa che è poco costoso e facile da imparare. Mentre è limitato nella sua capacità di separare adeguatamente estremamente grandi complessi, e non è stato universalmente successo, il metodo è stato in grado di catturare una vasta gamma di complessi ben studiato, ed è probabile applicabile a molti sistemi di interesse.

In questo esperimento di dimostrazione, multimero-PAGE è stata eseguita su tutto il lisato cervello di ratto. Le proteine ​​risultanti separati sono stati trasferiti su di polivinilidene (PVDF) diflouride membrane, e poi incubate con anticorpi contro le proteine ​​che sono noti per formare complessi. La figura 1 mostra una convalida del protocollo in due modi. In primo luogo, abbiamo dimostrato che le proteine reticolate sono scindibile mediante aggiunta di un a...

Watch this Scientific Journal Video about Multimer-PAGE: A Method for Capturing and Resolving Protein Complexes in Biological Samples at JoVE.com

Multimer-PAGE: A Method for Capturing and Resolving Protein Complexes in Biological Samples

Metodo per la stabilizzazione e la separazione complessi proteici nativi di lisato tessuto non modificato utilizzando una proteina reticolante amminico reattivo accoppiato ad un romanzo elettroforesi bidimensionale poliacrilammide sistema (PAGE) è presentato.

Multimer-PAGE: Un metodo per acquisire e risolvere i complessi proteici nei campioni biologici

There are many well-developed methods for purifying and studying single proteins and peptides. However, most cellular functions are carried out by ...

multimer-page-method-for-capturing-resolving-protein-complexes

Research

JoVE Journal

Biochemistry

11.3K Views.  Michigan State University.  Metodo per la stabilizzazione e la separazione complessi proteici nativi di lisato tessuto non modificato utilizzando una proteina reticolante amminico reattivo accoppiato ad un romanzo elettroforesi bidimensionale poliacrilammide sistema (PAGE) è presentato. 

Video: Multimer-PAGE: A Method for Capturing and Resolving Protein Complexes in Biological Samples

Sheathless Capillary Electrophoresis&#8211;Mass Spectrometry for Metabolic Profiling of Biological Samples

In metabolomics, a wide range of analytical techniques is used for the global profiling of (endogenous) metabolites in complex samples. In this paper, a protocol is presented for the analysis of anionic and cationic metabolites in biological samples by capillary electrophoresis&#8211;mass spectrometry (CE-MS). CE is well-suited for the analysis of highly polar and charged metabolites as compounds are separated on the basis of their charge-to-size ratio. A recently developed sheathless interfacing design, i.e., a porous tip interface, is used for coupling CE to electrospray ionization (ESI) MS. This interfacing approach allows the effective use of the intrinsically low-flow property of CE in combination with MS, resulting in nanomolar detection limits for a broad range of polar metabolite classes. The protocol presented here is based on employing a bare fused-silica capillary with a porous tip emitter at low-pH separation conditions for the analysis of a broad array of metabolite classes in biological samples. It is demonstrated that the same sheathless CE-MS method can be used for the profiling of cationic metabolites, including amino acids, nucleosides and small peptides, or anionic metabolites, including sugar phosphates, nucleotides and organic acids, by only switching the MS detection and separation voltage polarity. Highly information-rich metabolic profiles in various biological samples, such as urine, cerebrospinal fluid and extracts of the glioblastoma cell line, can be obtained by this protocol in less than 1 hr of CE-MS analysis.

A protocol for metabolic profiling of biological samples by capillary electrophoresis&#8211;mass spectrometry using a sheathless porous tip interface design is presented.

Guaina elettroforesi capillare-spettrometria di massa per metaboliche Profiling di campioni biologici

In metabolomics, a wide range of analytical techniques is used for the global profiling of (endogenous) metabolites in complex samples. In this paper, a ...

Ricerca

Biochimica

Method for Identifying Small Molecule Inhibitors of the Protein-protein Interaction Between HCN1 and TRIP8b

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed ubiquitously throughout the brain, where they function to regulate the excitability of neurons. The subcellular distribution of these channels in pyramidal neurons of hippocampal area CA1 is regulated by tetratricopeptide repeat-containing Rab8b interacting protein (TRIP8b), an auxiliary subunit. Genetic knockout of HCN pore forming subunits or TRIP8b, both lead to an increase in antidepressant-like behavior, suggesting that limiting the function of HCN channels may be useful as a treatment for Major Depressive Disorder (MDD). Despite significant therapeutic interest, HCN channels are also expressed in the heart, where they regulate rhythmicity. To circumvent off-target issues associated with blocking cardiac HCN channels, our lab has recently proposed targeting the protein-protein interaction between HCN and TRIP8b in order to specifically disrupt HCN channel function in the brain. TRIP8b binds to HCN pore forming subunits at two distinct interaction sites, although here the focus is on the interaction between the tetratricopeptide repeat (TPR) domains of TRIP8b and the C terminal tail of HCN1. In this protocol, an expanded description of a method for purifying TRIP8b and executing a high throughput screen to identify small molecule inhibitors of the interaction between HCN and TRIP8b, is described. The method for high throughput screening utilizes a Fluorescence Polarization (FP) -based assay to monitor the binding of a large TRIP8b fragment to a fluorophore-tagged eleven amino acid peptide corresponding to the HCN1 C terminal tail. This method allows &#39;hit&#39; compounds to be identified based on the change in the polarization of emitted light. Validation assays are then performed to ensure that &#39;hit&#39; compounds are not artifactual.

The interaction between HCN channels and their auxiliary subunit has been identified as a therapeutic target in Major Depressive Disorder. Here, a fluorescence polarization-based method for identifying small molecule inhibitors of this protein-protein interaction, is presented.

Metodo per identificare piccole molecole inibitori della interazione proteina-proteina tra HCN1 e TRIP8b

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed ubiquitously throughout the brain, where they function to regulate the ...

Time-resolved ElectroSpray Ionization Hydrogen-deuterium Exchange Mass Spectrometry for Studying Protein Structure and Dynamics

Intrinsically disordered proteins (IDPs) have long been a challenge to structural biologists due to their lack of stable secondary structure elements. Hydrogen-Deuterium Exchange (HDX) measured at rapid time scales is uniquely suited to detect structures and hydrogen bonding networks that are briefly populated, allowing for the characterization of transient conformers in native ensembles. Coupling of HDX to mass spectrometry offers several key advantages, including high sensitivity, low sample consumption and no restriction on protein size. This technique has advanced greatly in the last several decades, including the ability to monitor HDX labeling times on the millisecond time scale. In addition, by incorporating the HDX workflow onto a microfluidic platform housing an acidic protease microreactor, we are able to localize dynamic properties at the peptide level. In this study, Time-Resolved ElectroSpray Ionization Mass Spectrometry (TRESI-MS) coupled to HDX was used to provide a detailed picture of residual structure in the tau protein, as well as the conformational shifts induced upon hyperphosphorylation.

Conformational flexibility plays a critical role in protein function. Herein, we describe the use of time-resolved electrospray ionization mass spectrometry coupled to hydrogen-deuterium exchange for probing the rapid structural changes that drive function in ordered and disordered proteins.

Scambio risolta in tempo ionizzazione elettrospray idrogeno-deuterio Spettrometria di Massa per lo studio delle proteine ​​Struttura e dinamica

Intrinsically disordered proteins (IDPs) have long been a challenge to structural biologists due to their lack of stable secondary structure elements. ...

Resolving Affinity Purified Protein Complexes by Blue Native PAGE and Protein Correlation Profiling

Most proteins act in association with others; hence, it is crucial to characterize these functional units in order to fully understand biological processes. Affinity purification coupled to mass spectrometry (AP-MS) has become the method of choice for identifying protein-protein interactions. However, conventional AP-MS studies provide information on protein interactions, but the organizational information is lost. To address this issue, we developed a strategy to unravel the distinct functional assemblies a protein might be involved in, by resolving affinity-purified protein complexes prior to their characterization by mass spectrometry. Protein complexes isolated through affinity purification of a bait protein using an epitope tag and competitive elution are separated through blue native electrophoresis. Comparison of protein migration profiles through correlation profiling using quantitative mass spectrometry allows assignment of interacting proteins to distinct molecular entities. This method is able to resolve protein complexes of close molecular weights that might not be resolved by traditional chromatographic techniques such as gel filtration. With little more work than conventional AP-geLC-MS/MS, we demonstrate this strategy may in many cases be adequate for obtaining protein complex topological information concomitantly to identifying protein interactions.

Here we present protocols for affinity purification of protein complexes and their separation by blue native PAGE, followed by protein correlation profiling using label free quantitative mass spectrometry. This method is useful to resolve interactomes into distinct protein complexes.

Risoluzione purificato per affinità complessi proteici di Blue Native PAGE e proteine ​​correlazione Profiling

Most proteins act in association with others; hence, it is crucial to characterize these functional units in order to fully understand biological ...

Detection and Visualization of DNA Damage-induced Protein Complexes in Suspension Cell Cultures Using the Proximity Ligation Assay

The DNA damage response orchestrates the repair of DNA lesions that occur spontaneously, are caused by genotoxic stress, or appear in the context of programmed DNA breaks in lymphocytes. The Ataxia-Telangiectasia Mutated kinase (ATM), ATM- and Rad3-Related kinase (ATR) and the catalytic subunit of DNA-dependent Protein Kinase (DNA-PKcs) are among the first that are activated upon induction of DNA damage, and are central regulators of a network that controls DNA repair, apoptosis and cell survival. As part of a tumor-suppressive pathway, ATM and ATR activate p53 through phosphorylation, thereby regulating the transcriptional activity of p53. DNA damage also results in the formation of so-called ionizing radiation-induced foci (IRIF) that represent complexes of DNA damage sensor and repair proteins that accumulate at the sites of DNA damage, which are visualized by fluorescence microscopy. Co-localization of proteins in IRIFs, however, does not necessarily imply direct protein-protein interactions, as the resolution of fluorescence microscopy is limited. 
In situ Proximity Ligation Assay (PLA) is a novel technique that allows the direct visualization of protein-protein interactions in cells and tissues with unprecedented specificity and sensitivity. This technique is based on the spatial proximity of specific antibodies binding to the proteins of interest. When the interrogated proteins are within ~40 nm an amplification reaction is triggered by oligonucleotides that are conjugated to the antibodies, and the amplification product is visualized by fluorescent labeling, yielding a signal that corresponds to the subcellular location of the interacting proteins. Using the established functional interaction between ATM and p53 as an example, it is demonstrated here how PLA can be used in suspension cell cultures to study the direct interactions between proteins that are integral parts of the DNA damage response.

Here, it is demonstrated how the in situ Proximity Ligation Assay (PLA) can be used to detect and visualize the direct protein-protein interactions between ATM and p53 in suspension cell cultures exposed to genotoxic stress.

Rilevamento e visualizzazione di complessi proteici indotti da danni a DNA nelle cellule di cellule di sospensione utilizzando il test di legatura di prossimità

The DNA damage response orchestrates the repair of DNA lesions that occur spontaneously, are caused by genotoxic stress, or appear in the context of ...

Horizontal Gel Electrophoresis for Enhanced Detection of Protein-RNA Complexes

Native polyacrylamide gel electrophoresis is a fundamental tool of molecular biology that has been used extensively for the biochemical analysis of RNA-protein interactions. These interactions have been traditionally analyzed with polyacrylamide gels generated between two glass plates and samples electrophoresed vertically. However, polyacrylamide gels cast in trays and electrophoresed horizontally offers several advantages. For example, horizontal gels used to analyze complexes between fluorescent RNA substrates and specific proteins can be imaged multiple times as electrophoresis progresses. This provides the unique opportunity to monitor RNA-protein complexes at several points during the experiment. In addition, horizontal gel electrophoresis makes it possible to analyze many samples in parallel. This can greatly facilitate time course experiments as well as analyzing multiple reactions simultaneously to compare different components and conditions. Here we provide a detailed protocol for generating and using horizontal native gel electrophoresis for analyzing RNA-Protein interactions.

Native polyacrylamide gel electrophoresis is a fundamental tool for analyzing RNA-protein interactions. Traditionally most experiments have used vertical gels. However, horizontal gels provide several advantages, such as the opportunity to monitor complexes during electrophoresis. We provide a detailed protocol for generating and using horizontal native gel electrophoresis.

Elettroforesi gel orizzontale per la rilevazione avanzata dei complessi proteina-RNA

Native polyacrylamide gel electrophoresis is a fundamental tool of molecular biology that has been used extensively for the biochemical analysis of ...

2 in 1: One-step Affinity Purification for the Parallel Analysis of Protein-Protein and Protein-Metabolite Complexes

Cellular processes are regulated by interactions between biological molecules such as proteins, metabolites, and nucleic acids. While the investigation of protein-protein interactions (PPI) is no novelty, experimental approaches aiming to characterize endogenous protein-metabolite interactions (PMI) constitute a rather recent development. Herein, we present a protocol that allows simultaneous characterization of the PPI and PMI of a protein of choice, referred to as bait. Our protocol was optimized for Arabidopsis cell cultures and combines affinity purification (AP) with mass spectrometry (MS)-based protein and metabolite detection. In short, transgenic Arabidopsis lines, expressing bait protein fused to an affinity tag, are first lysed to obtain a native cellular extract. Anti-tag antibodies are used to pull down protein and metabolite partners of the bait protein. The affinity-purified complexes are extracted using a one-step methyl tert-butyl ether (MTBE)/methanol/water method. Whilst metabolites separate into either the polar or the hydrophobic phase, proteins can be found in the pellet. Both metabolites and proteins are then analyzed by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS or UPLC-MS/MS). Empty-vector (EV) control lines are used to exclude false positives. The major advantage of our protocol is that it enables identification of protein and metabolite partners of a target protein in parallel in near-physiological conditions (cellular lysate). The presented method is straightforward, fast, and can be easily adapted to biological systems other than plant cell cultures.

Protein-protein and protein-metabolite interactions are crucial for all cellular functions. Herein, we describe a protocol that allows parallel analysis of these interactions with a protein of choice. Our protocol was optimized for plant cell cultures and combines affinity purification with mass spectrometry-based protein and metabolite detection.

2 in 1: purificazione di affinità per l'analisi parallela di proteina-proteina e proteina-metabolita complessi in un unico passaggio

Cellular processes are regulated by interactions between biological molecules such as proteins, metabolites, and nucleic acids. While the investigation of ...

Use of Electron Paramagnetic Resonance in Biological Samples at Ambient Temperature and 77 K

The accurate and specific detection of reactive oxygen species (ROS) in different cellular and tissue compartments is essential to the study of redox-regulated signaling in biological settings. Electron paramagnetic resonance spectroscopy (EPR) is the only direct method to assess free radicals unambiguously. Its advantage is that it detects physiologic levels of specific species with a high specificity, but it does require specialized technology, careful sample preparation, and appropriate controls to ensure accurate interpretation of the data. Cyclic hydroxylamine spin probes react selectively with superoxide or other radicals to generate a nitroxide signal that can be quantified by EPR spectroscopy. Cell-permeable spin probes and spin probes designed to accumulate rapidly in the mitochondria allow for the determination of superoxide concentration in different cellular compartments.
In cultured cells, the use of cell permeable 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine (CMH) along with and without cell-impermeable superoxide dismutase (SOD) pretreatment, or use of cell-permeable PEG-SOD,&#160;allows for the differentiation of extracellular from cytosolic superoxide. The mitochondrial 1-hydroxy-4-[2-triphenylphosphonio)-acetamido]-2,2,6,6-tetramethyl-piperidine,1-hydroxy-2,2,6,6-tetramethyl-4-[2-(triphenylphosphonio)acetamido] piperidinium dichloride (mito-TEMPO-H) allows for measurement of mitochondrial ROS (predominantly superoxide).
Spin probes and EPR spectroscopy can also be applied to in vivo models. Superoxide can be detected in extracellular fluids such as blood and alveolar fluid, as well as tissues such as lung tissue. Several methods are presented to process and store tissue for EPR measurements and deliver intravenous 1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine (CPH) spin probe in vivo. While measurements can be performed at room temperature, samples obtained from in vitro and in vivo models can also be stored at -80 &#176;C and analyzed by EPR at 77 K. The samples can be stored in specialized tubing stable at -80 &#176;C and run at 77 K to enable a practical, efficient, and reproducible method that facilitates storing and transferring samples.

Electron paramagnetic resonance (EPR) spectroscopy is an unambiguous method to measure free radicals. The use of selective spin probes allows for detection of free radicals in different cellular compartments. We present a practical, efficient method to collect biological samples that facilitate treating, storing, and transferring samples for EPR measurements.

Uso di risonanza paramagnetica elettronica in campioni biologici a temperatura ambiente e 77 K

The accurate and specific detection of reactive oxygen species (ROS) in different cellular and tissue compartments is essential to the study of ...

Single-step Purification of Macromolecular Complexes Using RNA Attached to Biotin and a Photo-cleavable Linker

For many years, the exceptionally strong and rapidly formed interaction between biotin and streptavidin has been successfully utilized for partial purification of biologically important RNA/protein complexes. However, this strategy suffers from one major disadvantage that limits its broader utilization: the biotin/streptavidin interaction can be broken only under denaturing conditions that also disrupt the integrity of the eluted complexes, hence precluding their subsequent functional analysis and/or further purification by other methods. In addition, the eluted samples are frequently contaminated with the background proteins that nonspecifically associate with streptavidin beads, complicating the analysis of the purified complexes by silver staining and mass spectrometry. To overcome these limitations, we developed a variant of the biotin/streptavidin strategy in which biotin is attached to an RNA substrate via a photo-cleavable linker and the complexes immobilized on streptavidin beads are selectively eluted to solution in a native form by long wave UV, leaving the background proteins on the beads. Shorter RNA binding substrates can be synthesized chemically with biotin and the photo-cleavable linker covalently attached to the 5&#39; end of the RNA, whereas longer RNA substrates can be provided with the two groups by a complementary oligonucleotide. These two variants of the UV-elution method were tested for purification of the U7 snRNP-dependent processing complexes that cleave histone pre-mRNAs at the 3&#39; end and they both proved to compare favorably to other previously developed purification methods. The UV-eluted samples contained readily detectable amounts of the U7 snRNP that was free of major protein contaminants and suitable for direct analysis by mass spectrometry and functional assays. The described method can be readily adapted for purification of other RNA binding complexes and used in conjunction with single- and double-stranded DNA binding sites to purify DNA-specific proteins and macromolecular complexes.

RNA/protein complexes purified using botin-streptavidin strategy are eluted to solution under denaturing conditions in a form unsuitable for further purification and functional analysis. Here, we describe a modification of this strategy that utilizes a photo-cleavable linker in RNA and a gentle UV-elution step, yielding native and fully functional RNA/protein complexes.

Single-step purificazione di complessi macromolecolari usando RNA attaccato alla biotina e un Linker foto-spaccabili

For many years, the exceptionally strong and rapidly formed interaction between biotin and streptavidin has been successfully utilized for partial ...

Analysis of Protein Folding, Transport, and Degradation in Living Cells by Radioactive Pulse Chase

Radioactive pulse-chase labeling is a powerful tool for studying the conformational maturation, the transport to their functional cellular location, and the degradation of target proteins in live cells. By using short (pulse) radiolabeling times (&lt;30 min) and tightly controlled chase times, it is possible to label only a small fraction of the total protein pool and follow its folding. When combined with nonreducing/reducing SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoprecipitation with (conformation-specific) antibodies, folding processes can be examined in great detail. This system has been used to analyze the folding of proteins with a huge variation in properties such as soluble proteins, single and multi-pass transmembrane proteins, heavily N- and O-glycosylated proteins, and proteins with and without extensive disulfide bonding. Pulse-chase methods are the basis of kinetic studies into a range of additional features, including co- and posttranslational modifications, oligomerization, and polymerization, essentially allowing the analysis of a protein from birth to death. Pulse-chase studies on protein folding are complementary with other biochemical and biophysical methods for studying proteins in vitro by providing increased temporal resolution and physiological information. The methods as described within this paper are adapted easily to study the folding of almost any protein that can be expressed in mammalian or insect-cell systems.

Here we describe a protocol for a general pulse-chase method that allows the kinetic analysis of folding, transport, and degradation of proteins to be followed in live cells.

Analisi della piegatura della proteina, trasporto e degradazione in cellule viventi di radioattivo Pulse Chase

Radioactive pulse-chase labeling is a powerful tool for studying the conformational maturation, the transport to their functional cellular location, and ...