Nous tenons à remercier Quentina Beatty, Université de Linz, en Autriche, pour son aide genre, Katharina Strub, Université de Genève, en Suisse, pour la construction d&#39;hCD71-GFP, et Daniel Legler, Université de Constance, en Suisse, pour le GPI-GFP -DAF construire. Ce travail a été soutenu par le Fonds autrichien pour la science (FWF; projet Y250-B03) et le projet GEN-AU du Ministère fédéral autrichien pour la science et la recherche.

Impression par microcontact: <ol><li> Découpez domaine de Microdétail du timbre en PDMS aide d&#39;un scalpel </li><li> Lavez le champ contenant le Microdétail en le rinçant à l&#39;éthanol (100%) et de l&#39;eau distillée. </li><li> Sécher le timbre en PDMS à l&#39;azote ou de gaz argon. </li><li> Pipeter 50 ul solution BSA-Cy5 travaux (0,67 mg / ml) sur le timbre en PDMS afin que l&#39;ensemble du champ Microdétail est couverte de solution. Incuber pendant 30 min à température ambiante. </li><li> Lavez le domaine Microdétail en le rinçant à tampon phosphate salin (PBS) et de l&#39;eau distillée. </li><li> Sécher le PDMS à l&#39;azote ou de gaz argon. </li><li> Placez le timbre en PDMS sous son propre poids sur le milieu de l&#39;un revêtement époxy lamelle et incuber pendant 30 min à température ambiante dans une boîte de Pétri. </li><li> Étiquette de la position du timbre en PDMS sur le dos de la lamelle et la bande du timbre de la lame avec une pince. </li><li> Coller une chambre de fermeture sécurisée hybridation sur le champ microcontact-imprimée sur la lamelle. L&#39;étiquette permet de localiser le centre du terrain. </li><li> Pipeter 60 ul solution de travail de la streptavidine (50 pg / ml) dans la chambre de réaction et incuber l&#39;échantillon pendant 60 min à température ambiante. </li><li> Laver l&#39;échantillon avec 1 ml de PBS en ajoutant le tampon dans un port de la chambre et le retirer simultanément le second port avec une pompe. </li><li> Pipeter 60 pl solution biotinylé travaux d&#39;anticorps (10 ug / ml dans du PBS supplémenté avec 0,1% de Tween 20; &quot;PBST&quot;) dans la chambre de réaction et incuber pendant 60 min à température ambiante. </li><li> Laver l&#39;échantillon avec 1 ml PBST et ensuite 1 ml de PBS en ajoutant le tampon dans un port de la chambre et le retirer de nouveau à la deuxième port avec une pompe. </li><li> Stocker les surfaces micropatterned en PBS dans le noir à température ambiante jusqu&#39;à cellules sont prêtes pour l&#39;ensemencement. </li></ol> L&#39;incubation des cellules sur la surface micropatterned: <ol><li> Cultiver des cellules adhérentes à 50% de confluence dans une plaque de 3 cm de culture de tissu. </li><li> Détachez les cellules exprimant des protéines appâts et proies d&#39;intérêt avec l&#39;acide éthylènediamine (EDTA) et de solution de centrifugeuse 5 min à 1000 rpm. </li><li> Jeter le surnageant et dissoudre le culot cellulaire dans le milieu de croissance en fonction. </li><li> Centrifuger 5 min à 1000 rpm. </li><li> Jeter le surnageant et dissoudre le culot cellulaire dans un milieu de croissance approprié. </li><li> Bourse du PBS de la chambre de réaction sur la lamelle micropatterned par 60 pi de la suspension cellulaire. </li><li> Créer une chambre humidifiée par trempage d&#39;une compresse stérile dans l&#39;eau distillée et le mettre dans la boîte de Pétri pour empêcher l&#39;échantillon de tourner à sec. </li><li> Incuber les cellules pendant une nuit à 37 ° C dans une atmosphère de CO 2 5% sur les surfaces micropatterned. </li><li> Avant d&#39;analyser les cellules au microscope, l&#39;échange du milieu par une solution de Hank s saline tamponnée dont Ca 2 + et Mg 2 +. </li></ol> Microscopie: <ol><li> La lamelle est placée sur une monture adaptée et la morphologie des cellules est contrôlée dans la lumière blanche. </li><li> La qualité de la BSA-Cy5 modèles est vérifiée par une excitation à 647 nm. </li><li> Micropatterns de protéines proies fluorescente (GFP ou YFP) sont enregistrés à 488 ou 514 nm sous réflexion totale (TIR) ​​d&#39;excitation interne. </li></ol> Les résultats représentatifs: Si il ya une interaction entre les protéines cibles dans les cellules cultivées sur une surface micropatterned, la proie suivra la redistribution des appâts. Le Microdétail résultant peut être visualisé par le label de fluorescence de la protéine proie. Surtout le contraste obtenu fournit une mesure directe de la force d&#39;interaction (voir Figure 1). Par conséquent, une simple évaluation de l&#39;interaction des deux protéines devient possible - sans la nécessité de continuer à traiter les données mesurées primaire. <img src="/files/ftp_upload/1969/1969fig1.jpg" alt="Figure 1" /> Figure 1. Réarrangement de l&#39;appât dans la membrane plasmique de cellules vivantes à des forces d&#39;interaction différents. TIR images de cellules transfectées avec T24 (a) CD71-CD71-GFP sur des anticorps, (b) des CD4 et la YFP cytosolique sur les cellules CD4-anticorps et (c) GPI-GFP-DAF sur la CD59-anticorps microbiochips sont affichés. Les données sont caractéristiques de forte (a), non (b) ou interaction faible (c). (A) est reproduite à partir de (Weghuber et al., Sous presse), (b) de (Schwarzenbacher et al., 2008).

<ol>
	<li>Brameshuber, M., Schwarzenbacher, M., Kaltenbrunner, M., Hesch, C., Paster, W., Weghuber, J., Heise, B., Sonnleitner, A., Stockinger, H., Schuetz, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reply+to+"Uncoupling+diffusion+and+binding+in+FRAP+experiments.">Reply to "Uncoupling diffusion and binding in FRAP experiments.</a> Nat. Methods. 6, 183-184 (2009).</li><li>Kim, P. W., Sun, Z. J., Blacklow, S. C., Wagner, G., Eck, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Zinc+Clasp+Structure+Tethers+Lck+to+T+Cell+Coreceptors+CD4+and+CD8.">A Zinc Clasp Structure Tethers Lck to T Cell Coreceptors CD4 and CD8.</a> Science. 301, 1725-1728 (2003).</li><li>Ramm, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Image-based+screening:+a+technology+in+transition.">Image-based screening: a technology in transition.</a> Curr. Opin. Biotechnol. 16, 41-48 (2005).</li><li>Schwarzenbacher, M., Kaltenbrunner, M., Brameshuber, M., Hesch, C., Paster, W., Weghuber, J., Heise, B., Sonnleitner, A., Stockinger, H., Schutz, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micropatterning+for+quantitative+analysis+of+protein-protein+interactions+in+living+cells.">Micropatterning for quantitative analysis of protein-protein interactions in living cells.</a> Nat. Methods. 5, 1053-1060 (2008).</li><li>Weghuber, J., Brameshuber, M., Sunzenauer, S., Lehner, M., Paar, C., Haselbruebler, T., Schwarzenbacher, M., Kaltenbrunner, M., Paster, W., Heise, B., Sonnleitner, A., Stockinger, H., Schutz, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+protein-protein+interactions+in+the+live+cell+plasma+membrane+by+quantifying+prey+redistribution+upon+bait+micropatterning.">Detection of protein-protein interactions in the live cell plasma membrane by quantifying prey redistribution upon bait micropatterning.</a> Methods in Enzymology. , .</li></ol>

La vidéo contient des images qui ont été fournis par Olympus, tiré de la page d&#39;accueil du laboratoire de recherche de visualisation, l&#39;Université Brown ou reproduits à partir (Kim et al., 2003).

La vidéo qui l&#39;accompagne montre une méthode pour détecter les interactions protéine-protéine dans le plasma de la membrane des cellules vivantes (Schwarzenbacher et al, 2008;. Brameshuber et al, 2009;.. Weghuber et al, sous presse). En principe, n&#39;importe quelle plateforme de microscopie TIRF basé peut être utilisé comme système de lecture. Ce n&#39;est que lorsque la sensibilité élevée est souhaitée (par exemple pour la détection de molécules uniques), les microscopes de pointe seront nécessaires. Pour obtenir les meilleurs résultats les points critiques suivants pendant le processus de préparation nécessitent une attention particulière: <ol class="lroman"><li> Magasin de Cy5-solution-mère dans des conditions sombres pour éviter le blanchiment du fluorophore et préparer la BSA-Cy5 solution de travail fraîchement avant l&#39;impression par microcontact. </li><li> Attention à ne pas rayer la Microdétail sur le PDMS avec la pointe de la pipette et incuber l&#39;échantillon dans des conditions sombres pour éviter le blanchiment du fluorophore. </li><li> Mettez la lamelle sur une compresse stérile pour empêcher le collage de la lame de verre pour la boîte de Pétri. Une fois le timbre en PDMS a adhéré à la lame de verre, ne pas le déplacer. </li><li> Eviter les bulles d&#39;air dans la chambre de réaction et incuber l&#39;échantillon dans des conditions sombres pour éviter le blanchiment du fluorophore. </li><li> Ne laissez pas l&#39;échantillon sec pendant plus de 2 minutes pour éviter la formation de cristaux de sel. </li><li> Pour le détachement des cellules de ne pas utiliser la trypsine comme il cliver le domaine extracellulaire de protéines membranaires jusqu&#39;à présent exprimé. Eviter la trypsine sera utile pour les protéines avec faible taux de rotation pour former micropatterns immédiatement après la fixation des cellules sur la surface. </li><li> Contrôle le nombre de cellules incubées dans un microscope et faire en sorte que les cellules n&#39;atteignent pas plus de 30-50% de confluence. Assurez-vous que les cellules excès sont enlevés immédiatement en raison de la fixation rapide des cellules sur la surface revêtue d&#39;anticorps. </li><li> Seules les diapositives de haute qualité BSA-Cy5 modèles peuvent être utilisés pour une analyse ultérieure. </li><li> Une expression stable de la protéine fluorescente est préférable proies due à une plus grande nombre de cellules qui peuvent être analysées par balayage. </li><li> Adéquate de réglage FRBR est indispensable pour visualiser les modèles en raison de fond cytosolique. </li></ol> La technique de micro-motifs propose plusieurs possibilités pour l&#39;analyse des interactions protéine-protéine. Tout d&#39;abord, avec la quantification des locaux, résolues spatialement interactions protéine-protéine a également la détection des interactions faibles ou indirecte n&#39;est possible sans l&#39;inconvénient de donner un nombre élevé de faux positifs ou négatifs. Deuxièmement, elle permet au chercheur d&#39;analyser les interactions entre protéines dans le plasma de la membrane des cellules vivantes, ce qui est difficile à réaliser par des approches biochimiques comme l&#39;écran 2-hybride. Troisièmement, l&#39;approche permet la détection de l&#39;appât-proie interactions qui sont modulés par les changements environnementaux comme la température, la présence de différentes protéines ou autres molécules ou modifications post-traductionnelles. Ainsi, le test de dépistage permet de modulateurs de l&#39;interaction d&#39;une paire donnée dans le contexte de cellules vivantes. Par ailleurs, en réduisant la densité de surface du ligand de capture ou de l&#39;utilisation de ligands monovalents, l&#39;analyse de l&#39;état de repos devient possible. Enfin, si les plates-formes adéquates de numérisation sont utilisés, le nombre de cellules analysées est suffisamment élevé pour correspondre à la demande haut débit des entreprises pharmaceutiques pour le dépistage de drogue (Ramm, 2005).

in-vivo detection of protein-protein interactions on micro-patterned surfaces

Démêler le réseau d&#39;interaction des molécules<em&gt; In vivo</em&gt; Est la clé de la compréhension des mécanismes qui régulent la fonction cellulaire et du métabolisme. Une multitude d&#39;options méthodologiques pour aborder les interactions moléculaires dans les cellules ont été développés, mais la plupart de ces méthodes souffrent d&#39;être plutôt indirect et par conséquent guère quantitatives. Au contraire, quelques-uns de haut de gamme des approches quantitatives ont été introduites, qui sont toutefois difficile à étendre à haut débit. Pour combiner des capacités haut débit avec la possibilité d&#39;extraire des informations quantitatives, nous avons récemment développé un nouveau concept d&#39;identification des interactions protéine-protéine (Schwarzenbacher<em&gt; Et al</em&gt;., 2008). Ici, nous décrivons un protocole détaillé pour la conception et la construction de ce système qui permet d&#39;analyser les interactions entre un fluorophore protéine marquée («proie») et une protéine de membrane («appât»)<em&gt; In vivo</em&gt;. Les cellules sont étalées sur des surfaces fonctionnalisées micropatterned avec des anticorps contre le domaine des appâts exoplasmic. Appât-proie interactions sont analysés à travers la redistribution de la proie fluorescentes. La méthode est caractérisée par une sensibilité élevée jusqu&#39;au niveau de molécules uniques, la capacité de détecter des interactions faibles, et la capacité de débit élevé, rendant applicable comme outil de dépistage.

Watch this Scientific Journal Video about In-vivo Detection of Protein-protein Interactions on Micro-patterned Surfaces at JoVE.com

In-vivo Detection of Protein-protein Interactions on Micro-patterned Surfaces

Cette vidéo montre des expériences avec l&#39;analyse subséquente des interactions protéine-protéine par l&#39;utilisation de micro-surfaces texturées. L&#39;approche offre la possibilité de détecter les interactions entre protéines dans les cellules vivantes et combine haute capacité de débit avec la possibilité d&#39;extraire des informations quantitatives.

In vivo de détection des interactions protéine-protéine sur la micro-surfaces texturées

Unraveling the interaction network of molecules in-vivo is key to understanding the mechanisms that regulate cell function and metabolism. A multitude of ...

in-vivo-detection-protein-protein-interactions-on-micro-patterned

Research

JoVE Journal

Biology

In-vivo Detection of Protein-protein Interactions on Micro-patterned Surfaces

10.7K vues.  Johannes Kepler Universitat Linz. Cette vidéo montre des expériences avec l'analyse subséquente des interactions protéine-protéine par l'utilisation de micro-surfaces texturées. L'approche offre la possibilité de détecter les interactions entre protéines dans les cellules vivantes et combine haute capacité de débit avec la possibilité d'extraire des informations quantitatives.

Vidéo: In-vivo Detection of Protein-protein Interactions on Micro-patterned Surfaces

Split-Ubiquitin Based Membrane Yeast Two-Hybrid (MYTH) System: A Powerful Tool For Identifying Protein-Protein Interactions

The fundamental biological and clinical importance of integral membrane proteins prompted the development of a yeast-based system for the high-throughput identification of protein-protein interactions (PPI) for full-length transmembrane proteins. To this end, our lab developed the split-ubiquitin based Membrane Yeast Two-Hybrid (MYTH) system. This technology allows for the sensitive detection of transient and stable protein interactions using Saccharomyces cerevisiae as a host organism. MYTH takes advantage of the observation that ubiquitin can be separated into two stable moieties: the C-terminal half of yeast ubiquitin (Cub) and the N-terminal half of the ubiquitin moiety (Nub). In MYTH, this principle is adapted for use as a 'sensor' of protein-protein interactions. Briefly, the integral membrane bait protein is fused to Cub which is linked to an artificial transcription factor. Prey proteins, either in individual or library format, are fused to the Nub moiety. Protein interaction between the bait and prey leads to reconstitution of the ubiquitin moieties, forming a full-length 'pseudo-ubiquitin' molecule. This molecule is in turn recognized by cytosolic deubiquitinating enzymes, resulting in cleavage of the transcription factor, and subsequent induction of reporter gene expression. The system is highly adaptable, and is particularly well-suited to high-throughput screening. It has been successfully employed to investigate interactions using integral membrane proteins from both yeast and other organisms.

Split-Ubiquitin Based Membrane Yeast Two-Hybrid MYTH System: A Powerful Tool For Identifying Protein-Protein Interactions

MYTH allows the sensitive detection of transient and stable interactions between proteins that are expressed in the model organism Saccharomyces cerevisiae. It has been successfully applied to study exogenous and yeast integral membrane proteins in order to identify their interacting partners in a high throughput manner.

Split-ubiquitine membrane à base de levure double hybride (MYTH) Système: Un outil puissant pour identifier les interactions entre protéines

The fundamental biological and clinical importance of integral membrane proteins prompted the development of a yeast-based system for the high-throughput ...

Recherche

Biologie

Imaging Protein-protein Interactions in vivo

Protein-protein interactions are a hallmark of all essential cellular processes. However, many of these interactions are transient, or energetically weak, preventing their identification and analysis through traditional biochemical methods such as co-immunoprecipitation. In this regard, the genetically encodable fluorescent proteins (GFP, RFP, etc.) and their associated overlapping fluorescence spectrum have revolutionized our ability to monitor weak interactions in vivo using F&ouml;rster resonance energy transfer (FRET)1-3. Here, we detail our use of a FRET-based proximity assay for monitoring receptor-receptor interactions on the endothelial cell surface.

Imaging Protein-protein Interactions in vivo

This protocol describes how to image protein-protein interactions using a FRET-based proximity assay.

Imagerie interactions protéine-protéine In vivo</em

Protein-protein interactions are a hallmark of all essential cellular processes. However, many of these interactions are transient, or energetically weak, ...

In vivo Quantification of G Protein Coupled Receptor Interactions using Spectrally Resolved Two-photon Microscopy

The study of protein interactions in living cells is an important area of research because the information accumulated both benefits industrial applications as well as increases basic fundamental biological knowledge. F&ouml;rster (Fluorescence) Resonance Energy Transfer (FRET) between a donor molecule in an electronically excited state and a nearby acceptor molecule has been frequently utilized for studies of protein-protein interactions in living cells. The proteins of interest are tagged with two different types of fluorescent probes and expressed in biological cells. The fluorescent probes are then excited, typically using laser light, and the spectral properties of the fluorescence emission emanating from the fluorescent probes is collected and analyzed. Information regarding the degree of the protein interactions is embedded in the spectral emission data. Typically, the cell must be scanned a number of times in order to accumulate enough spectral information to accurately quantify the extent of the protein interactions for each region of interest within the cell. However, the molecular composition of these regions may change during the course of the acquisition process, limiting the spatial determination of the quantitative values of the apparent FRET efficiencies to an average over entire cells. By means of a spectrally resolved two-photon microscope, we are able to obtain a full set of spectrally resolved images after only one complete excitation scan of the sample of interest. From this pixel-level spectral data, a map of FRET efficiencies throughout the cell is calculated. By applying a simple theory of FRET in oligomeric complexes to the experimentally obtained distribution of FRET efficiencies throughout the cell, a single spectrally resolved scan reveals stoichiometric and structural information about the oligomer complex under study. Here we describe the procedure of preparing biological cells (the yeast Saccharomyces cerevisiae) expressing membrane receptors (sterile 2 &alpha;-factor receptors) tagged with two different types of fluorescent probes. Furthermore, we illustrate critical factors involved in collecting fluorescence data using the spectrally resolved two-photon microscopy imaging system. The use of this protocol may be extended to study any type of protein which can be expressed in a living cell with a fluorescent marker attached to it.

In vivo Quantification of G Protein Coupled Receptor Interactions using Spectrally Resolved Two-photon Microscopy

By employing a spectrally resolved two-photon microscopy imaging system, pixel-level maps of F&ouml;rster Resonance Energy Transfer (FRET) efficiencies are obtained for cells expressing membrane receptors hypothesized to form homo-oligomeric complexes. From the FRET efficiency maps, we are able to estimate stoichiometric information about the oligomer complex under study.

Dans la quantification in vivo des interactions des protéines G récepteurs couplés utilisant résolution spectrale microscopie à deux photons

The study of protein interactions in living cells is an important area of research because the information accumulated both benefits industrial ...

A Protocol for the Identification of Protein-protein Interactions Based on 15N Metabolic Labeling, Immunoprecipitation, Quantitative Mass Spectrometry and Affinity Modulation

Protein-protein interactions are fundamental for many biological processes in the cell. Therefore, their characterization plays an important role in current research and a plethora of methods for their investigation is available1. Protein-protein interactions often are highly dynamic and may depend on subcellular localization, post-translational modifications and the local protein environment2. Therefore, they should be investigated in their natural environment, for which co-immunoprecipitation approaches are the method of choice3. Co-precipitated interaction partners are identified either by immunoblotting in a targeted approach, or by mass spectrometry (LC-MS/MS) in an untargeted way. The latter strategy often is adversely affected by a large number of false positive discoveries, mainly derived from the high sensitivity of modern mass spectrometers that confidently detect traces of unspecifically precipitating proteins. A recent approach to overcome this problem is based on the idea that reduced amounts of specific interaction partners will co-precipitate with a given target protein whose cellular concentration is reduced by RNAi, while the amounts of unspecifically precipitating proteins should be unaffected. This approach, termed QUICK for QUantitative Immunoprecipitation Combined with Knockdown4, employs Stable Isotope Labeling of Amino acids in Cell culture (SILAC)5 and MS to quantify the amounts of proteins immunoprecipitated from wild-type and knock-down strains. Proteins found in a 1:1 ratio can be considered as contaminants, those enriched in precipitates from the wild type as specific interaction partners of the target protein. Although innovative, QUICK bears some limitations: first, SILAC is cost-intensive and limited to organisms that ideally are auxotrophic for arginine and/or lysine. Moreover, when heavy arginine is fed, arginine-to-proline interconversion results in additional mass shifts for each proline in a peptide and slightly dilutes heavy with light arginine, which makes quantification more tedious and less accurate5,6. Second, QUICK requires that antibodies are titrated such that they do not become saturated with target protein in extracts from knock-down mutants.
Here we introduce a modified QUICK protocol which overcomes the abovementioned limitations of QUICK by replacing SILAC for 15N metabolic labeling and by replacing RNAi-mediated knock-down for affinity modulation of protein-protein interactions. We demonstrate the applicability of this protocol using the unicellular green alga Chlamydomonas reinhardtii as model organism and the chloroplast HSP70B chaperone as target protein7 (Figure 1). HSP70s are known to interact with specific co-chaperones and substrates only in the ADP state8. We exploit this property as a means to verify the specific interaction of HSP70B with its nucleotide exchange factor CGE19.

A Protocol for the Identification of Protein-protein Interactions Based on 15N Metabolic Labeling, Immunoprecipitation, Quantitative Mass Spectrometry and Affinity Modulation

We present a variation of the QUICK (QUantitative Immunoprecipitation Combined with Knockdown) approach that was introduced previously to distinguish between true and false protein-protein interactions. Our approach is based on 15N metabolic labeling, the modulation of affinities of protein-protein interactions by the presence/absence of ATP, immunoprecipitation, and quantitative mass spectrometry.

Un protocole pour l&#39;identification des interactions protéine-protéine Basé sur<sup&gt; 15</sup&gt; N marquage métabolique, immunoprécipitation, la spectrométrie de masse quantitative et d&#39;affinité de modulation

Protein-protein interactions are fundamental for many biological processes in the cell. Therefore, their characterization plays an important role in ...

Protein-protein Interactions Visualized by Bimolecular Fluorescence Complementation in Tobacco Protoplasts and Leaves

Many proteins interact transiently with other proteins or are integrated into multi-protein complexes to perform their biological function. Bimolecular fluorescence complementation (BiFC) is an in vivo method to monitor such interactions in plant cells. In the presented protocol the investigated candidate proteins are fused to complementary halves of fluorescent proteins and the respective constructs are introduced into plant cells via agrobacterium-mediated transformation. Subsequently, the proteins are transiently expressed in tobacco leaves and the restored fluorescent signals can be detected with a confocal laser scanning microscope in the intact cells. This allows not only visualization of the interaction itself, but also the subcellular localization of the protein complexes can be determined. For this purpose, marker genes containing a fluorescent tag can be coexpressed along with the BiFC constructs, thus visualizing cellular structures such as the endoplasmic reticulum, mitochondria, the Golgi apparatus or the plasma membrane. The fluorescent signal can be monitored either directly in epidermal leaf cells or in single protoplasts, which can be easily isolated from the transformed tobacco leaves. BiFC is ideally suited to study protein-protein interactions in their natural surroundings within the living cell. However, it has to be considered that the expression has to be driven by strong promoters and that the interaction partners are modified due to fusion of the relatively large fluorescence tags, which might interfere with the interaction mechanism. Nevertheless, BiFC is an excellent complementary approach to other commonly applied methods investigating protein-protein interactions, such as coimmunoprecipitation, in vitro pull-down assays or yeast-two-hybrid experiments.

Formation of protein complexes in vivo can be visualized by bimolecular fluorescence complementation. Interaction partners are fused to complementary parts of fluorescent tags and transiently expressed in tobacco leaves, resulting in a reconstituted fluorescent signal upon close proximity of the two proteins.

Interactions protéine-protéine visualisés par fluorescence bimoléculaire complémentation en protoplastes de tabac et des feuilles

Many proteins interact transiently with other proteins or are integrated into multi-protein complexes to perform their biological function. Bimolecular ...

Investigating Protein-protein Interactions in Live Cells Using Bioluminescence Resonance Energy Transfer

Assays based on Bioluminescence Resonance Energy Transfer (BRET) provide a sensitive and reliable means to monitor protein-protein interactions in live cells. BRET is the non-radiative transfer of energy from a 'donor' luciferase enzyme to an 'acceptor' fluorescent protein. In the most common configuration of this assay, the donor is Renilla reniformis luciferase and the acceptor is Yellow Fluorescent Protein (YFP). Because the efficiency of energy transfer is strongly distance-dependent, observation of the BRET phenomenon requires that the donor and acceptor be in close proximity. To test for an interaction between two proteins of interest in cultured mammalian cells, one protein is expressed as a fusion with luciferase and the second as a fusion with YFP. An interaction between the two proteins of interest may bring the donor and acceptor sufficiently close for energy transfer to occur. Compared to other techniques for investigating protein-protein interactions, the BRET assay is sensitive, requires little hands-on time and few reagents, and is able to detect interactions which are weak, transient, or dependent on the biochemical environment found within a live cell. It is therefore an ideal approach for confirming putative interactions suggested by yeast two-hybrid or mass spectrometry proteomics studies, and in addition it is well-suited for mapping interacting regions, assessing the effect of post-translational modifications on protein-protein interactions, and evaluating the impact of mutations identified in patient DNA.

Interactions between proteins are fundamental to all cellular processes. Using Bioluminescence Resonance Energy Transfer, the interaction between a pair of proteins can be monitored in live cells and in real time. Furthermore, the effects of potentially pathogenic mutations can be assessed.

Étudier les interactions protéine-protéine dans les cellules vivantes en utilisant le transfert d&#39;énergie de résonance de bioluminescence

Assays based on Bioluminescence Resonance Energy Transfer (BRET) provide a sensitive and reliable means to monitor protein-protein interactions in live ...

Probing High-density Functional Protein Microarrays to Detect Protein-protein Interactions

High-density functional protein microarrays containing ~4,200 recombinant yeast proteins are examined for kinase protein-protein interactions using an affinity purified yeast kinase fusion protein containing a V5-epitope tag for read-out. Purified kinase is obtained through culture of a yeast strain optimized for high copy protein production harboring a plasmid containing a Kinase-V5 fusion construct under a GAL inducible promoter. The yeast is grown in restrictive media with a neutral carbon source for 6 hr followed by induction with 2% galactose. Next, the culture is harvested and kinase is purified using standard affinity chromatographic techniques to obtain a highly purified protein kinase for use in the assay. The purified kinase is diluted with kinase buffer to an appropriate range for the assay and the protein microarrays are blocked prior to hybridization with the protein microarray. After the hybridization, the arrays are probed with monoclonal V5 antibody to identify proteins bound by the kinase-V5 protein. Finally, the arrays are scanned using a standard microarray scanner, and data is extracted for downstream informatics analysis1,2 to determine a high confidence set of protein interactions for downstream validation in vivo.

Using protein microarrays containing nearly the entire S. cerevisiae proteome is probed for rapid unbiased interrogation of thousands of protein-protein interactions in parallel. This method can be utilized for protein-small molecule, posttranslational modification, and other assays in high-throughput.

Sondage haute densité fonctionnels des puces à protéines pour détecter les interactions protéine-protéine

High-density functional protein microarrays containing ~4,200 recombinant yeast proteins are examined for kinase protein-protein interactions using an ...

Development of Inhibitors of Protein-protein Interactions through REPLACE: Application to the Design and Development Non-ATP Competitive CDK Inhibitors

REPLACE is a unique strategy developed to more effectively target protein-protein interactions (PPIs). It aims to expand available drug target space by providing improved methodology for the identification of inhibitors for such binding sites and which represent the majority of potential drug targets. The main goal of this paper is to provide a methodological overview of the use and application of the REPLACE strategy which involves computational and synthetic chemistry approaches. REPLACE is exemplified through its application to the development of non-ATP competitive cyclin dependent kinases (CDK) inhibitors as anti-tumor therapeutics. CDKs are frequently deregulated in cancer and hence are considered as important targets for drug development. Inhibition of CDK2/cyclin A in S phase has been reported to promote selective apoptosis of cancer cells in a p53 independent manner through the E2F1 pathway. Targeting the protein-protein interaction at the cyclin binding groove (CBG) is an approach which will allow the specific inhibition of cell cycle over transcriptional CDKs. The CBG is recognized by a consensus sequence derived from CDK substrates and tumor suppressor proteins termed the cyclin binding motif (CBM). The CBM has previously been optimized to an octapeptide from p21Waf (HAKRRIF) and then further truncated to a pentapeptide retaining sufficient activity (RRLIF). Peptides in general are not cell permeable, are metabolically unstable and therefore the REPLACE (REplacement with Partial Ligand Alternatives through Computational Enrichment) strategy has been applied in order to generate more drug-like inhibitors. The strategy begins with the design of Fragment ligated inhibitory peptides (FLIPs) that selectively inhibit cell cycle CDK/cyclin complexes. FLIPs were generated by iteratively replacing residues of HAKRRLIF/RRLIF with fragment like small molecules (capping groups), starting from the N-terminus (Ncaps), followed by replacement on the C-terminus. These compounds are starting points for the generation of non-ATP competitive CDK inhibitors as anti-tumor therapeutics.

We describe implementation of the REPLACE strategy for targeting protein-protein interactions. REPLACE is an iterative strategy involving synthetic and computational approaches for the conversion of optimized peptidic inhibitors into drug like molecules.

Développement d&#39;inhibiteurs de interactions protéine-protéine REMPLACER travers: Application à la conception et les inhibiteurs de CDK concurrentiel développement non-ATP

REPLACE is a unique strategy developed to more effectively target protein-protein interactions (PPIs). It aims to expand available drug target space by ...

Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo

Intricate gene regulatory networks orchestrate biological processes and developmental transitions in plants. Selective transcriptional activation and silencing of genes mediate the response of plants to environmental signals and developmental cues. Therefore, insights into the mechanisms that control plant gene expression are essential to gain a deep understanding of how biological processes are regulated in plants. The chromatin immunoprecipitation (ChIP) technique described here is a procedure to identify the DNA-binding sites of proteins in genes or genomic regions of the model species Arabidopsis thaliana. The interactions with DNA of proteins of interest such as transcription factors, chromatin proteins or posttranslationally modified versions of histones can be efficiently analyzed with the ChIP protocol. This method is based on the fixation of protein-DNA interactions in vivo, random fragmentation of chromatin, immunoprecipitation of protein-DNA complexes with specific antibodies, and quantification of the DNA associated with the protein of interest by PCR techniques. The use of this methodology in Arabidopsis has contributed significantly to unveil transcriptional regulatory mechanisms that control a variety of plant biological processes. This approach allowed the identification of the binding sites of the Arabidopsis chromatin protein EBS to regulatory regions of the master gene of flowering FT. The impact of this protein in the accumulation of particular histone marks in the genomic region of FT was also revealed through ChIP analysis.

Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo

Chromatin immunoprecipitation is a powerful technique for the identification of DNA binding sites of Arabidopsis proteins in vivo. This procedure includes chromatin cross-linking and fragmentation, immunoprecipitation with selective antibodies against the protein of interest, and qPCR analysis of bound DNA. We describe a simple ChIP assay optimized for Arabidopsis plants.

Immunoprécipitation de la chromatine test pour l&#39;identification de Arabidopsis interactions protéine-ADN<em&gt; In Vivo</em

Intricate gene regulatory networks orchestrate biological processes and developmental transitions in plants. Selective transcriptional activation and ...

Study of Protein-protein Interactions in Autophagy Research

Protein-protein interactions are important for understanding cellular signaling cascades and identifying novel pathway components and protein dynamics. The majority of cellular activities require physical interactions between proteins. To analyze and map these interactions, various experimental techniques as well as bioinformatics tools were developed. Autophagy is a cellular recycling mechanism that allows the cells to cope with different stressors, including nutrient deprivation, chemicals, and hypoxia. In order to better understand autophagy-related signaling events and to discover novel factors that regulate protein complexes in autophagy, we performed protein-protein interaction screens. Validation of these screening results requires the use of immunofluorescence and immunoprecipitation techniques. In this system, specific autophagy-related protein-protein interactions that we discovered were tested in Neuro2A (N2A) and HEK293T cell lines. Details of the technical procedures used are explained in this visualized experiment paper.

Presented here are two antibody-based protein-protein interaction research techniques: immunofluorescence and immunoprecipitation. These techniques are suitable for studying physical interactions between proteins for the discovery of novel components of cellular signaling pathways and for understanding protein dynamics.

Étude des Interactions protéine-protéine dans la recherche de l’autophagie

Protein-protein interactions are important for understanding cellular signaling cascades and identifying novel pathway components and protein dynamics. ...