Wir danken Michael Reth, Hermann Schägger und Margarita Camacho-Carvajal für die wissenschaftliche Unterstützung. Diese Arbeit wurde von FORSYS vom Bundesministerium fuer Bildung und Forschung (BMBF) gefördert, durch BIOSS von der Deutschen Forschungsgemeinschaft (DFG), und unterstützt zum Teil durch die Exzellenzinitiative der deutschen Bundesregierung und der Länder (GSC-4, Spemann Graduiertenschule ).

<ol>
	<li>Arnold, I., Pfeiffer, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Yeast+mitochondrial+F1F0-ATP+synthase+exists+as+a+dimer:+identification+of+three+dimer-specific+subunits.">Yeast mitochondrial F1F0-ATP synthase exists as a dimer: identification of three dimer-specific subunits.</a> EMBO J. 17 (24), 7170-7178 (1998).</li><li>Camacho-Carvajal, M. M., Wollscheid, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two-dimensional+Blue+native/SDS+gel+electrophoresis+of+multi-protein+complexes+from+whole+cellular+lysates:+a+proteomics+approach.">Two-dimensional Blue native/SDS gel electrophoresis of multi-protein complexes from whole cellular lysates: a proteomics approach.</a> Mol. Cell. Proteomics. 3 (2), 176-182 (2004).</li><li>Heiss, K., Junkes, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subproteomic+analysis+of+metal-interacting+proteins+in+human+B+cells.">Subproteomic analysis of metal-interacting proteins in human B cells.</a> Proteomics. 5 (14), 3614-3622 (2005).</li><li>Sali, A., Glaeser, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+words+to+literature+in+structural+proteomics.">From words to literature in structural proteomics.</a> Nature. 422, 216-225 (2003).</li><li>Schägger, H., Cramer, W. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+molecular+masses+and+oligomeric+states+of+protein+complexes+by+blue+native+electrophoresis+and+isolation+of+membrane+protein+complexes+by+two-dimensional+native+electrophoresis.">Analysis of molecular masses and oligomeric states of protein complexes by blue native electrophoresis and isolation of membrane protein complexes by two-dimensional native electrophoresis.</a> Anal. Biochem. 217 (2), 220-230 (1994).</li><li>Sch&#228;gger, H., von Jagow, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blue+native+electrophoresis+for+isolation+of+membrane+protein+complexes+in+enzymatically+active+form.">Blue native electrophoresis for isolation of membrane protein complexes in enzymatically active form.</a> Anal. Biochem. 199 (2), 223-231 (1991).</li><li>Schamel, W. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biotinylation+of+protein+complexes+may+lead+to+aggregation+as+well+as+to+loss+of+subunits+as+revealed+by+Blue+Native+PAGE.">Biotinylation of protein complexes may lead to aggregation as well as to loss of subunits as revealed by Blue Native PAGE.</a> J Immunol Methods. 252 (1-2), 171-174 (2001).</li><li>Schamel, W. W., Arechaga, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coexistence+of+multivalent+and+monovalent+TCRs+explains+high+sensitivity+and+wide+range+of+response.">Coexistence of multivalent and monovalent TCRs explains high sensitivity and wide range of response.</a> J. Exp. Med. 202, 493-503 (2005).</li><li>Schamel, W. W., Reth, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monomeric+and+oligomeric+complexes+of+the+B+cell+antigen+receptor.">Monomeric and oligomeric complexes of the B cell antigen receptor.</a> Immunity. 13 (1), 5-14 (2000).</li><li>Swamy, M., Minguet, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+native+antibody-based+mobility-shift+technique+(NAMOS-assay)+to+determine+the+stoichiometry+of+multiprotein+complexes.">A native antibody-based mobility-shift technique (NAMOS-assay) to determine the stoichiometry of multiprotein complexes.</a> J Immunol Methods. 324 (1-2), 74-83 (2007).</li><li>Swamy, M., Siegers, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blue+native+polyacrylamide+gel+electrophoresis+(BN-PAGE)+for+the+identification+and+analysis+of+multiprotein+complexes.">Blue native polyacrylamide gel electrophoresis (BN-PAGE) for the identification and analysis of multiprotein complexes.</a> Sci STKE. 2006 (345), 4-4 (2006).</li><li>Wittig, I., Schagger, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Features+and+applications+of+blue-native+and+clear-native+electrophoresis.">Features and applications of blue-native and clear-native electrophoresis.</a> Proteomics. 8, 3974-3990 (2008).</li></ol>

In dieser Studie beschreiben wir die Analyse der PLM nach BN-PAGE. Ein 2D-Ansatz ist die erste eigenständige MPC unter nativen Bedingungen verwendet werden, und dann weiter zu unterteilen sie in ihre einzelnen Komponenten durch eine zweite Dimension SDS-PAGE. Die Proben werden aus Zelllysaten vorbereitet. Für die Solubilisierung von vielen Mittelmeer-Partnerländer, ist ein geeignetes Reinigungsmittel benötigt, die bewahrt die Struktur des Protein-Komplexen. Hier verwenden wir 0,1% Triton X-100. Allerdings haben die optimale Reinigungs-und ihrer geeigneten Konzentration empirisch für jeden MPC bestimmt werden. Im Falle von Triton X-100 zum Beispiel wurde berichtet, dass niedrige Detergenzkonzentrationen die Identifizierung einer dimeren Form des F 1 ermöglichen F 0-ATPase-Komplex (Arnold, Pfeiffer et al. 1998). Höhere Triton X-100-Konzentrationen, jedoch auf die Dissoziation des Dimers und zu einer entsprechenden Erhöhung der monomeren F 1 F 0-ATPase-Komplexes führen. Dies steht im Einklang mit einem unserer früheren Studien konnten wir zeigen, dass die multivalente T-Zell-Rezeptor-Komplex (TCR) erhalten bleibt, wenn sie mit geringen Konzentrationen von Brij 96 extrahiert, während die Verwendung von höheren Konzentrationen oder eines anderen Waschmittel genannt Digitonin Ergebnisse in die Gewinnung von monomerem TCR (Schamel, Arechaga et al. 2005). Häufig verwendete Reinigungsmittel, die getestet werden können, gehören Digitonin (0,5 bis 1%), Triton X-100 (0,1 bis 0,5%), Brij 96 (0,1 bis 0,5%), oder Dodecylmaltosid (0,1 bis 0,5%). Diese Reagenzien sind ionische Detergenzien, die am besten für MPC Stabilität neigen. Seien Sie sich bewusst, dass der Kontakt mit SDS und andere scharfe Reinigungsmittel sollten vermieden (Camacho-Carvajal, Wollscheid et al. 2004). Dialyse der Lysate wird benötigt, um MPC Trennung in einem BN-Gel (Camacho-Carvajal, Wollscheid et al 2004). Erzielen; (Heiss, Junkes et al 2005).. Es scheint, dass die Einstellung der Salzkonzentration oder die Entfernung von Verunreinigungen mit niedrigem Molekulargewicht entscheidend für eine hohe Auflösung. Es ist bemerkenswert, dass auch Membran-Präparationen und MPC, die seit immunopurified haben und später aus dem Antikörper eluiert, geeignet für BN-PAGE werden (Swamy, Siegers et al. 2006). In beiden Fällen müssen die Proben nicht für BN-PAGE Trennung dialysiert werden, wenn Membran Lyse oder Elution erfolgt in BN-Lysepuffer durchgeführt. Für Protein Trennung durch BN-PAGE, wird der Farbstoff Coomassie-Blau benötigt, was bindet unspezifisch an Proteine ​​und bedeckt sie mit negativen Ladungen. Dadurch ermöglicht die Coomassie-Blau der elektrophoretischen Mobilität von Proteinen in Richtung der Kathode bei neutralem pH (Schägger und von Jagow 1991); (Schägger, Cramer et al 1994).. Darüber hinaus verhindert Coomassieblau Proteinaggregation in den Stapeln Gel während der Elektrophorese. Für BN-PAGE wurde Coomassie G250, um anstelle von Coomassie Blau R250 oder kolloidale Coomassie Blau verwendet werden. Bevor Sie eine BN-Gel, ist es notwendig, um sicherzustellen, dass der Anteil des Gels auf die erwartete Größe des MPC von Interesse passt. Vorgefertigte BN-Gele mit unterschiedlichen Steigungen und geeignete Puffer sind im Handel erhältlich von Invitrogen (NativePAGE Novex Bis-Tris Gel System). Aber BN-Gele können auch unter Verwendung eines Gradientenmischer zusammen mit einem persistaltic pumpen. Um zu gewährleisten, eine intakte Gradienten, sollte die Flüssigkeit fließen ständig während des Gießens und Blasen zu vermeiden. Wir empfehlen das Laden von verschiedenen Probenverdünnungen auf das Gel weil Überlastung kann zu Proteinfällung während der Elektrophorese-Verfahren führen. Darüber hinaus sollten BN-Gels bei 4 laufen ° C bis Proteinabbau zu verhindern und zu halten, den Mittelmeer-Partnerländern intakt. Nach BN-PAGE, Visualisierung der Mittelmeer-Partnerländer durch Coomassie Brilliant Blue-Färbung, Silberfärbung oder Immunoblotting erreicht werden. Proteinbanden sichtbar gemacht durch Coomassie-oder Silberfärbung sind für die weitere Analyse geeignet durch Massenspektrometrie (Camacho-Carvajal, Wollscheid et al. 2004). Im Falle von Immunoblot, haben die optimale Übertragung Bedingungen für die Mittelmeer-Partnerländer von Interesse sind empirisch ermittelt werden. Seien Sie sich bewusst, dass Coomassie-Blau auch während Blotting einer BN-Gel übertragen. Daher wird das Gel nach dem erfolgreichen Transfer farblos, während die Membran eine blaue Farbe ausüben wird. Darüber hinaus ist es wichtig zu erwähnen, dass nicht jeder primärer Antikörper, die für den Nachweis nach SDS-PAGE arbeitet, für Immunoblot auf BN-PAGE ist. Es kann vorkommen, dass Antikörper erkennen nicht die MPC von Interesse, weil ihre Epitop in die native Konformation der Proteine ​​verborgen ist. Um dieses Problem zu überwinden, ist es möglich, die Proteine ​​innerhalb der BN-Gel vor der Übertragung durch Kochen denaturiert das Gel kurz in 1x SDS-Probenpuffer. In unserem Beispiel haben wir nicht unter dem BN-Gel direkt auf die Erfassung Proteinbanden. Stattdessen haben wir weiter unterteilt die BN-PAGE getrennt Lysat durch eine zweite dimensiauf SDS-PAGE. In der zweiten Dimension SDS-Gel, monomere Proteine ​​innerhalb einer hyperbolischen diagonal durch die Gradienten-Gel in der ersten und der linear-Gel in der zweiten Dimension (Camacho-Carvajal, Wollscheid et al. 2004) zu migrieren. Dies ermöglicht die einfache Identifizierung der Mittelmeer-Partnerländer, da sie unterhalb dieser hyperbolischen Diagonale lokalisiert sind. Unterkomponenten einer deutlichen MPC sind in einer vertikalen Linie in der zweiten Dimension SDS-PAGE getrennt. Komponenten, die Bestandteile von mehreren dinstinct MPCs sind, können auf einer horizontalen Linie nach der Größe der MPC identifiziert werden. Es ist jedoch zu berücksichtigen, dass mehrere Proteinspots erscheinen in einer vertikalen Linie könnte auch ein Teil der getrennten Komplexen, die an der gleichen Position in BN-PAGE wandern werden. Der endgültige Beweis, dass sie in der gleichen MPC sind, können durch einen Antikörper-basierte Gel-Shift-Assay erhalten. In diesem Assay wird Zelllysat mit einem Antikörper gegen ein Protein, das von einem der identifizierten Spots vor der BN-PAGE vertreten inkubiert. Dies führt zu einer Verschiebung aller MPCs, dass dieses Protein enthalten, zu einem höheren Molekulargewicht in der ersten Dimension. Andere Proteine, die auch ein Teil dieser MPCs wird durchlaufen diese komplexe spezifische Schicht und sind deshalb leicht in die zweite Dimension SDS-Gel zu identifizieren. Nicht nur die Zusammensetzung der Mittelmeer-Partnerländer durch BN-PAGE analysiert werden, sondern auch die Bestimmung ihrer Stöchiometrie ist möglich (Schamel und Reth 2000); (Schamel 2001), (Swamy, Minguet et al 2007).. Zu diesem Zweck kann ein NAMOS Assay (native Antikörper-basierte Mobility-Shift-Assay) durchgeführt werden. Wie in der Antikörper-basierte Gel-Shift-Assay werden die zellulären Lysaten mit monoklonalen Untereinheit-spezifischen Antikörper inkubiert. Dies führt zur Induktion der elektrophoretischen immunoshifts in der BN-Gele, die den Schluss erlauben aus dem Ausmaß der Verschiebung von der Stöchiometrie der MPC In SCHLUSSKOMMENTAR ist BN-PAGE geeignet für die Identifizierung von MPL und die Bestimmung ihrer Größe, Zusammensetzung, sowie relative Häufigkeit. Aufgeführt als NAMOS Assay, es bietet auch die Möglichkeit, die Stöchiometrie einer bestimmten MPC bestimmen. Aufgrund seiner allgemeinen Anwendbarkeit, ist diese Technik ein sehr nützliches Werkzeug für die Charakterisierung von PLM (Dekker, Müller et al 1996.); (Wittig und Schagger 2008); (Wagner, Rehling et al 2009.); (Wittig und Schägger 2009) .

blue native polyacrylamide gel electrophoresis (bn-page) for analysis of multiprotein complexes from cellular lysates

Multiproteinkomplexen (MPL) spielen eine entscheidende Rolle für die Zellkommunikation, da die meisten Proteine ​​in funktioneller oder regulatorische Komplexe mit anderen Proteinen (Sali, Glaeser et al. 2003) gefunden werden kann. So erfordert die Untersuchung von Protein-Protein-Interaktions-Netzwerke die detaillierte Charakterisierung der Mittelmeer-Partnerländer, um ein integratives Verständnis der Funktion von Proteinen und Regulierung zu gewinnen. Zur Identifizierung und Analyse muss MPCs unter nativen Bedingungen getrennt werden. In diesem Video, beschreiben wir die Analyse der Mittelmeer-Partnerländer durch blaue nativen Polyacrylamidgelelektrophorese (BN-PAGE). BN-PAGE ist eine Technik, die Trennung von MPC ermöglicht in einer nativen Konformation mit einer höheren Auflösung als durch Gelfiltration oder Saccharose-Dichtegradienten-Ultrazentrifugation angeboten und ist daher sinnvoll, MPC Größe, Zusammensetzung und relative Häufigkeit (Schägger und von Jagow 1991) bestimmen ; (Schägger, Cramer et al 1994).. Mit dieser Methode werden Proteine ​​nach ihrer hydrodynamischen Größe und Form in einem Polyacrylamid-Matrix getrennt. Hier zeigen wir die Analyse der Mittelmeer-Partnerländer der gesamten zellulären Lysaten und wies darauf hin, dass Lysat Dialyse den entscheidenden Schritt zu machen BN-PAGE für diese biologischen Proben ist. Mit einer Kombination aus der ersten Dimension BN-und die zweite Dimension SDS-PAGE zeigen wir, dass PLM nach BN-PAGE getrennt weiter in ihre einzelnen Bestandteile werden durch SDS-PAGE unterteilt. Visualisierung der MPC-Komponenten auf Gel-Trennung wird durch Standard-Immunblot durchgeführt. Als Beispiel für MPC Analyse von BN-PAGE, wählten wir die gut charakterisierten eukaryotischen 19S, 20S und 26S Proteasomen.

Watch this Scientific Journal Video about Blue Native Polyacrylamide Gel Electrophoresis BN-PAGE for Analysis of Multiprotein Complexes from Cellular Lysates at JoVE.com

Blue Native Polyacrylamide Gel Electrophoresis BN-PAGE for Analysis of Multiprotein Complexes from Cellular Lysates

In diesem Video, beschreiben wir die Charakterisierung von Multiproteinkomplexen (MPL) durch blaue nativen Polyacrylamidgelelektrophorese (BN-PAGE). In einer ersten Dimension sind dialysiert Zelllysaten durch BN-PAGE getrennt an die einzelnen MPL zu identifizieren. In einer zweiten Dimension SDS-PAGE, werden MPC von Interesse weiter unterteilt, um ihre Wähler durch Immunoblot analysieren.

Blaue Native Polyacrylamid-Gelelektrophorese (BN-PAGE) zur Analyse von Multiproteinkomplexen aus Zelllysaten

Multiprotein complexes (MPCs) play a crucial role in cell signalling, since most proteins can be found in functional or regulatory complexes with other ...

blue-native-polyacrylamide-gel-electrophoresis-bn-page-for-analysis

Research

JoVE Journal

Biology

Blue Native Polyacrylamide Gel Electrophoresis (BN-PAGE) for Analysis of Multiprotein Complexes from Cellular Lysates

130.8K Aufrufe.  University of Freiburg. In diesem Video, beschreiben wir die Charakterisierung von Multiproteinkomplexen (MPL) durch blaue nativen Polyacrylamidgelelektrophorese (BN-PAGE). In einer ersten Dimension sind dialysiert Zelllysaten durch BN-PAGE getrennt an die einzelnen MPL zu identifizieren. In einer zweiten Dimension SDS-PAGE, werden MPC von Interesse weiter unterteilt, um ihre Wähler durch Immunoblot analysieren.

Serie: Blue Native Polyacrylamide Gel Electrophoresis BN-PAGE for Analysis of Multiprotein Complexes from Cellular Lysates

Denaturing Gradient Gel Electrophoresis (DGGE)

Denaturing Gradient Gel Electrophoresis DGGE

Okay.Hi, my name is Celeste Peterson and I'm a fellow at Harvard University studying microbial bio film communities. So I am profiling the bacterial communities by looking at their 60 N sequence and how this sequence changes over time in space. And to do that, I'm using DDGE.This is not a normal acry of my well, it needs to be kept at 60 degrees when it's run and the buffer needs to be pumped continuously. So we're gonna warm up the buffer for about an hour until it's at 60 degrees, and then we can run the towel. Now I'm gonna wash this plate with dilute uc solution, peeling around for impurities, andone, light that up.Anything like that can cause regularities. It is important to wipe off all the water. So when I assemble the gel, I'll put that chip on the outside of the gel.So the gel will be in between these two pieces of glass and the chip will be on the outside and it won't affect the gel in between. So now I'm gonna assemble the gel in these clamps and then I squeeze them together and tighten by turning to the right. As with any gel, it's important to make sure that the bottom is flush.To prevent making, we now turn the gel around and put it in here to get sealed with the gasket. So it's important when you do this that the gel, that the plates are actually lined up with the gasket here. So these knobs on the side then go in and you press down to type the seal.So this is a 30 mil syringe. And this part and this part come with the bio red kit and it just on like this. And that's just to get rid of the excess water in the tubes.So put the tubing onto the gel to load the gel. First you put an adapter into the tubing and then a needle look with that small adapter and put it right in the center of the gel just so it's fairly below the bottom glass. Then this wire adapter goes into the long tubing and it's going to connect to equal syringes containing the high and the low density solution.So these are pre-prepared solutions. The blue one, I've added a dye here that just indicates that this is the most denaturing solution and this is the least fitting train solution, the low density one. And they have everything in them.And now I'm gonna to make, gonna be Actually I twice as much the week. And once you've got the tempt, you have about five to seven minutes to fill the gel before the colon rises. And now we fill the syringe juice with the solution.So I'm gonna fill it with about 15 the solution. And then to get rid of any air bubbles, I'll turn it upside down and squeeze gently until that top air bubble is gone. Now this little screw here is gonna go into this groove.This adapter is gonna line up with this clamp here, and it's gonna get C clamped in very tightly. And then this tubing is gonna attach to the syringe. And the same thing is done on the other side with the high density matrix where it's time to deliver.And so I'm gonna be turning this wheel in a steady clockwise motion. And first the blue solution is gonna go out first because that's the the most in nature, and it's gonna form the bottom part of the gel. And then after a little while, the clear solution will start filling in the gel and the Gradient will be formed.One moment is the gently on an angle to And as soon as you finish pouring the gel to wash out your tubes immediately because they will polymerize Going, It's the group there. And then press down. So this little, And on the other side, I'll do the same thing.Okay.Hi, my name is Celeste Peterson and I'm a fellow at Harvard University studying microbial bio communities. So I am profiling the bacterial communities by looking at their 60 F sequence and how the sequence changes over time in space. And to do that, I'm using DDGE.So DGE is Dena gel electrophoresis. And basically the idea is that there's a gradient and the DNA, as it runs down the gradient gets de natured. And so different 16 species will stop at different points along the gradient.And so it ends up being a fingerprint of the different sexiness species in the community. So the goal of my experiment is to see who is in the community and how that's changing over time and space. And I can run the sexiness DDD gel and then I can cut out the bands and identify the species that are represented in each community.So one of the biggest issues when, when doing A DDG gel is to figure out the gradient that's the best. And so that is just something that needs to be played around with and figuring out for a particular community which type of gradient. So the one I'm using today is 35 to 55%urea.One of the big problems that can happen with this technique is that smears come up in in the leans. And I found for that, for whatever reason, one of the best things to do is to run the gels for a really long time and then the smears disappear. Well, today I'm just using it for general bacterial communities, but this can also be used for a specific family of bacteria to see how those change over time, and those tend to be very clean gels.You can also look at mutations in single genes with DDGE.

Denaturierende Gradienten-Gelelektrophorese (DGGE)

Forschung

Biologie

Screening for Amyloid Aggregation by Semi-Denaturing Detergent-Agarose Gel Electrophoresis

Amyloid aggregation is associated with numerous protein misfolding pathologies and underlies the infectious properties of prions, which are conformationally self-templating proteins that are thought to have beneficial roles in lower organisms.  Amyloids have been notoriously difficult to study due to their insolubility and structural heterogeneity.  However, resolution of amyloid polymers based on size and detergent insolubility has been made possible by Semi-Denaturing Detergent-Agarose Gel Electrophoresis (SDD-AGE).  This technique is finding widespread use for the detection and characterization of amyloid conformational variants.  Here, we demonstrate an adaptation of this technique that facilitates its use in large-scale applications, such as screens for novel prions and other amyloidogenic proteins.  The new SDD-AGE method uses capillary transfer for greater reliability and ease of use, and allows any sized gel to be accomodated.  Thus, a large number of samples, prepared from cells or purified proteins, can be processed simultaneously for the presence of SDS-insoluble conformers of tagged proteins.

SDD-AGE is a useful technique for the detection and characterization of amyloid-like polymers in cells. Here we demonstrate an adaptation that makes this technique amenable to large-scale applications.

Screening für Amyloid-Aggregation durch Semi-denaturierenden Detergens-Agarose-Gel-Elektrophorese

Amyloid aggregation is associated with numerous protein misfolding pathologies and underlies the infectious properties of prions, which are ...

Identification of protein complexes with quantitative proteomics in S. cerevisiae

Lipids are the building blocks of cellular membranes that function as barriers and in compartmentalization of cellular processes, and recently, as important intracellular signalling molecules. However, unlike proteins, lipids are small hydrophobic molecules that traffic primarily by poorly described nonvesicular routes, which are hypothesized to occur at membrane contact sites (MCSs). MCSs are regions where the endoplasmic reticulum (ER) makes direct physical contact with a partnering organelle, e.g., plasma membrane (PM). The ER portion of ER-PM MCSs is enriched in lipid-synthesizing enzymes, suggesting that lipid synthesis is directed to these sites and implying that MCSs are important for lipid traffic. Yeast is an ideal model to study ER-PM MCSs because of their abundance, with over 1000 contacts per cell, and their conserved nature in all eukaryotes. Uncovering the proteins that constitute MCSs is critical to understanding how lipids traffic is accomplished in cells, and how they act as signaling molecules. We have found that an ER called Scs2p localize to ER-PM MCSs and is important for their formation. We are focused on uncovering the molecular partners of Scs2p. Identification of protein complexes traditionally relies on first resolving purified protein samples by gel electrophoresis, followed by in-gel digestion of protein bands and analysis of peptides by mass spectrometry. This often limits the study to a small subset of proteins. Also, protein complexes are exposed to denaturing or non-physiological conditions during the procedure. To circumvent these problems, we have implemented a large-scale quantitative proteomics technique to extract unbiased and quantified data. We use stable isotope labeling with amino acids in cell culture (SILAC) to incorporate staple isotope nuclei in proteins in an untagged control strain. Equal volumes of tagged culture and untagged, SILAC-labeled culture are mixed together and lysed by grinding in liquid nitrogen. We then carry out an affinity purification procedure to pull down protein complexes. Finally, we precipitate the protein sample, which is ready for analysis by high-performance liquid chromatography/ tandem mass spectrometry. Most importantly, proteins in the control strain are labeled by the heavy isotope and will produce a mass/ charge shift that can be quantified against the unlabeled proteins in the bait strain. Therefore, contaminants, or unspecific binding can be easily eliminated. By using this approach, we have identified several novel proteins that localize to ER-PM MCSs. Here we present a detailed description of our approach. 

Here we describe a new quantitative proteomics technique for identifying protein complexes in Saccharomyces cerevisiae. In this study, we have used the SILAC method together with affinity purification followed by tandem mass spectrometry to identify with high specificity the binding partners of an ER protein, Scs2p.

Identifizierung von Protein-Komplexen mit der quantitativen Proteomik in S. cerevisiae

Lipids are the building blocks of cellular membranes that function as barriers and in compartmentalization of cellular processes, and recently, as ...

Denaturing Urea Polyacrylamide Gel Electrophoresis (Urea PAGE)

Urea PAGE or denaturing urea polyacrylamide gel electrophoresis employs 6-8 M urea, which denatures secondary DNA or RNA structures and is used for their separation in a polyacrylamide gel matrix based on the molecular weight. Fragments between 2 to 500 bases, with length differences as small as a single nucleotide, can be separated using this method1. The migration of the sample is dependent on the chosen acrylamide concentration. A higher percentage of polyacrylamide resolves lower molecular weight fragments. The combination of urea and temperatures of 45-55 &deg;C during the gel run allows for the separation of unstructured DNA or RNA molecules.
In general this method is required to analyze or purify single stranded DNA or RNA fragments, such as synthesized or labeled oligonucleotides or products from enzymatic cleavage reactions.
In this video article we show how to prepare and run the denaturing urea polyacrylamide gels. Technical tips are included, in addition to the original protocol 1,2.

Denaturing Urea Polyacrylamide Gel Electrophoresis Urea PAGE

Denaturing urea polyacrylamide gel electrophoresis is used to separate single-stranded DNA or RNA up to a limit of 500 nucleotides. Urea in combination with heat denatures samples and unstructured single strands migrate within the gel matrix according to their molecular weight.

Denaturierung Urea Polyacrylamidgelelektrophorese (Urea PAGE)

Urea PAGE or denaturing urea polyacrylamide gel electrophoresis employs 6-8 M urea, which denatures secondary DNA or RNA structures and is used for their ...

Agarose Gel Electrophoresis for the Separation of DNA Fragments

Agarose gel electrophoresis is the most effective way of separating DNA fragments of varying sizes ranging from 100 bp to 25 kb1. Agarose is isolated from the seaweed genera Gelidium and Gracilaria, and consists of repeated agarobiose (L- and D-galactose) subunits2. During gelation, agarose polymers associate non-covalently and form a network of bundles whose pore sizes determine a gel&#39;s molecular sieving properties. The use of agarose gel electrophoresis revolutionized the separation of DNA. Prior to the adoption of agarose gels, DNA was primarily separated using sucrose density gradient centrifugation, which only provided an approximation of size. To separate DNA using agarose gel electrophoresis, the DNA is loaded into pre-cast wells in the gel and a current applied. The phosphate backbone of the DNA (and RNA) molecule is negatively charged, therefore when placed in an electric field, DNA fragments will migrate to the positively charged anode. Because DNA has a uniform mass/charge ratio, DNA molecules are separated by size within an agarose gel in a pattern such that the distance traveled is inversely proportional to the log of its molecular weight3. The leading model for DNA movement through an agarose gel is &#34;biased reptation&#34;, whereby the leading edge moves forward and pulls the rest of the molecule along4. The rate of migration of a DNA molecule through a gel is determined by the following: 1) size of DNA molecule; 2) agarose concentration; 3) DNA conformation5; 4) voltage applied, 5) presence of ethidium bromide, 6) type of agarose and 7) electrophoresis buffer. After separation, the DNA molecules can be visualized under uv light after staining with an appropriate dye. By following this protocol, students should be able to: 
 
1. Understand the mechanism by which DNA fragments are separated within a gel matrix 
2. Understand how conformation of the DNA molecule will determine its mobility through a gel matrix 
3. Identify an agarose solution of appropriate concentration for their needs 
4. Prepare an agarose gel for electrophoresis of DNA samples 
5. Set up the gel electrophoresis apparatus and power supply 
6. Select an appropriate voltage for the separation of DNA fragments 
7. Understand the mechanism by which ethidium bromide allows for the visualization of DNA bands 
8. Determine the sizes of separated DNA fragments 
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A basic protocol for the separation of DNA fragments using agarose gel electrophoresis is described.

Agarosegel-Elektrophorese für die Trennung von DNA-Fragmenten

Agarose gel electrophoresis is the most effective way of separating DNA fragments of varying sizes ranging from 100 bp to 25 kb1. Agarose is isolated from ...

Rapid Generation of Amyloid from Native Proteins In vitro

Proteins carry out crucial tasks in organisms by exerting functions elicited from their specific three dimensional folds. Although the native structures of polypeptides fulfill many purposes, it is now recognized that most proteins can adopt an alternative assembly of beta-sheet rich amyloid. Insoluble amyloid fibrils are initially associated with multiple human ailments, but they are increasingly shown as functional players participating in various important cellular processes. In addition, amyloid deposited in patient tissues contains nonproteinaceous components, such as nucleic acids and glycosaminoglycans (GAGs). These cofactors can facilitate the formation of amyloid, resulting in the generation of different types of insoluble precipitates. By taking advantage of our understanding how proteins misfold via an intermediate stage of soluble amyloid precursor, we have devised a method to convert native proteins to amyloid fibrils in vitro. This approach allows one to prepare amyloid in large quantities, examine the properties of amyloid generated from specific proteins, and evaluate the structural changes accompanying the conversion.

Rapid Generation of Amyloid from Native Proteins In vitro

Proteins can either adopt a native structure or misfold into insoluble amyloid. Conditions that favor the misfolding pathway lead to the formation of different types of amyloid fibrils. The methods described here allow rapid conversion of native proteins into amyloid in vitro.

Proteins carry out crucial tasks in organisms by exerting functions elicited from their specific three dimensional folds. Although the native structures ...

A New Approach for the Comparative Analysis of Multiprotein Complexes Based on 15N Metabolic Labeling and Quantitative Mass Spectrometry

The introduced protocol provides a tool for the analysis of multiprotein complexes in the thylakoid membrane, by revealing insights into complex composition under different conditions. In this protocol the approach is demonstrated by comparing the composition of the protein complex responsible for cyclic electron flow (CEF) in Chlamydomonas reinhardtii, isolated from genetically different strains. The procedure comprises the isolation of thylakoid membranes, followed by their separation into multiprotein complexes by sucrose density gradient centrifugation, SDS-PAGE, immunodetection and comparative, quantitative mass spectrometry (MS) based on differential metabolic labeling (14N/15N) of the analyzed strains. Detergent solubilized thylakoid membranes are loaded on sucrose density gradients at equal chlorophyll concentration. After ultracentrifugation, the gradients are separated into fractions, which are analyzed by mass-spectrometry based on equal volume. This approach allows the investigation of the composition within the gradient fractions and moreover to analyze the migration behavior of different proteins, especially focusing on ANR1, CAS, and PGRL1. Furthermore, this method is demonstrated by confirming the results with immunoblotting and additionally by supporting the findings from previous studies (the identification and PSI-dependent migration of proteins that were previously described to be part of the CEF-supercomplex such as PGRL1, FNR, and cyt f). Notably, this approach is applicable to address a broad range of questions for which this protocol can be adopted and e.g. used for comparative analyses of multiprotein complex composition isolated from distinct environmental conditions.

A New Approach for the Comparative Analysis of Multiprotein Complexes Based on 15N Metabolic Labeling and Quantitative Mass Spectrometry

The described comparative, quantitative proteomic approach aims at obtaining insights into the composition of multiprotein complexes&#160;under different conditions and is demonstrated by comparing genetically different strains. For quantitative analysis equal volumes of different fractions from a sucrose density gradient are mixed and analyzed by mass spectrometry.

Ein neuer Ansatz für die vergleichende Analyse von Multiproteinkomplexen Basierend auf<sup&gt; 15</sup&gt; N Metabolische Markierung und quantitative Massenspektrometrie

The introduced protocol provides a tool for the analysis of multiprotein complexes in the thylakoid membrane, by revealing insights into complex ...

AFM-based Mapping of the Elastic Properties of Cell Walls: at Tissue, Cellular, and Subcellular Resolutions

We describe a recently developed method to measure mechanical properties of the surfaces of plant tissues using atomic force microscopy (AFM) micro/nano-indentations, for a JPK&#160;AFM. Specifically, in this protocol we measure the apparent Young&#8217;s modulus of cell walls at subcellular resolutions across regions of up to 100 &#181;m&#160;x 100 &#181;m in floral meristems, hypocotyls, and roots. This requires careful preparation of the sample, the correct selection of micro-indenters and indentation depths. To account for cell wall properties only, measurements are performed in highly concentrated solutions of mannitol in order to plasmolyze the cells and thus remove the contribution of cell turgor pressure.
In contrast to other extant techniques, by using different indenters and indentation depths, this method allows simultaneous multiscale measurements, i.e. at subcellular resolutions and across hundreds of cells comprising a tissue. This means that it is now possible&#160;to spatially-temporally characterize the changes that take place in the mechanical properties of cell walls during development, enabling these changes to be correlated with growth and differentiation. This represents a key step to understand how coordinated microscopic cellular changes bring about macroscopic morphogenetic events.
However, several limitations remain: the method can only be used on fairly small samples (around 100 &#181;m in diameter) and only on external tissues; the method is sensitive to tissue topography; it measures only certain aspects of the tissue&#8217;s complex mechanical properties. The technique is being developed rapidly and it is likely that most of these limitations will be resolved in the near future.

We describe a method to map mechanical properties of plant tissues using an atomic force microscope (AFM). We focus on how to record mechanical changes that take place in cell walls during plant development at wide-field mesoscale, enabling these changes to be correlated with growth and morphogenesis.

AFM-basierte Mapping der elastischen Eigenschaften der Zellwände: auf der Tissue-, Handy-und subzellulärer Beschlüsse

We describe a recently developed method to measure mechanical properties of the surfaces of plant tissues using atomic force microscopy (AFM) ...

Mucin Agarose Gel Electrophoresis: Western Blotting for High-molecular-weight Glycoproteins

Mucins, the heavily-glycosylated proteins lining mucosal surfaces, have evolved as a key component of innate defense by protecting the epithelium against invading pathogens. The main role of these macromolecules is to facilitate particle trapping and clearance while promoting lubrication of the mucosa. During protein synthesis, mucins undergo intense O-glycosylation and multimerization, which dramatically increase the mass and size of these molecules. These post-translational modifications are critical for the viscoelastic properties of mucus. As a result of the complex biochemical and biophysical nature of these molecules, working with mucins provides many challenges that cannot be overcome by conventional protein analysis methods. For instance, their high-molecular-weight prevents electrophoretic migration via regular polyacrylamide gels and their sticky nature causes adhesion to experimental tubing. However, investigating the role of mucins in health (e.g., maintaining mucosal integrity) and disease (e.g., hyperconcentration, mucostasis, cancer) has recently gained interest and mucins are being investigated as a therapeutic target. A better understanding of the production and function of mucin macromolecules may lead to novel pharmaceutical approaches, e.g., inhibitors of mucin granule exocytosis and/or mucolytic agents. Therefore, consistent and reliable protocols to investigate mucin biology are critical for scientific advancement. Here, we describe conventional methods to separate mucin macromolecules by electrophoresis using an agarose gel, transfer protein into nitrocellulose membrane, and detect signal with mucin-specific antibodies as well as infrared fluorescent gel reader. These techniques are widely applicable to determine mucin quantitation, multimerization and to test the effects of pharmacological compounds on mucins.

Mucins are high-molecular-weight glycoconjugates, with size ranging from 0.2 to 200 megadalton (MDa). As a result of their size, mucins do not penetrate conventional polyacrylamide gels and require larger pores for separation. We provide a detailed protocol for mucin agarose gel electrophoresis to assess relative quantification and study polymer assembly.

Mucin Agarose-Gel-Elektrophorese: Western Blotting für Hochmolekulare Glykoproteine


Mucins, the heavily-glycosylated proteins lining mucosal surfaces, have evolved as a key component of innate defense by protecting the epithelium against ...

Purification of Native Complexes for Structural Study Using a Tandem Affinity Tag Method

Affinity purification approaches have been successful in isolating native complexes for proteomic characterization. Structural heterogeneity and a degree of compositional heterogeneity of a complex do not usually impede progress in conducting such studies. In contrast, a complex intended for structural characterization should be purified in a state that is both compositionally and structurally homogeneous as well as at a higher concentration than required for proteomics. Recently, there have been significant advances in the application of electron microscopy for structure determination of large macromolecular complexes. This has heightened interest in approaches to purify native complexes of sufficient quality and quantity for structural determination by electron microscopy. The Tandem Affinity Purification (TAP) method has been optimized to extract and purify an 18-subunit, ~ 0.8 MDa ribonucleoprotein assembly from budding yeast (Saccharomyces cerevisiae) suitable for negative stain and electron cryo microscopy. Herein is detailed the modifications made to the TAP method, the rationale for making these changes, and the approaches taken to assay for a compositionally and structurally homogeneous complex.

The Tandem Affinity Purification (TAP) method has been used extensively to isolate native complexes from cellular extract, primarily eukaryotic, for proteomics. Here, we present a TAP method protocol optimized for purification of native complexes for structural studies.

Reinigung von nativem Komplexe für die Strukturstudie ein Tandem Affinity Tag-Methode unter Einsatz

Affinity purification approaches have been successful in isolating native complexes for proteomic characterization. Structural heterogeneity and a degree ...

Blaue Native Polyacrylamid-Gelelektrophorese (BN-PAGE) zur Analyse von Multiproteinkomplexen aus Zelllysaten

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