Name: multimer-page: a method for capturing and resolving protein complexes in biological samples
Uploaded: 2017-05-05T14:00:00
Description: Watch this Scientific Journal Video about Multimer-PAGE: A Method for Capturing and Resolving Protein Complexes in Biological Samples at JoVE.com

Supported by the NIH/NIDA DA034783. We thank Bryan A. Killinger for technical assistance with the multimer-PAGE.

1. Tissue Preparation
<ol>
	<li>Prepare 10 mL of 4x BN-PAGE sample buffer (200 mM Bis(2-hydroxyethyl)amino-tris(hydroxymethyl)methane (Bis-Tris), 200 mM NaCl, 40% w/v glycerol, 0.004% Ponceau S, pH 7.2). 
	NOTE: This stock solution may be made in advance and stored at 4 &#176;C.</li>
	<li>Dilute 250 &#181;L of 4x sample buffer in 750 &#181;L dH2O containing 1x commercial protease inhibitor cocktail. Vortex and chill on ice.</li>
	<li>Homogenize 20 mg of target tissue in the 1 mL 1x ice-cold BN-PAGE samp...

<ol>
	<li>Alberts, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+cell+as+a+collection+of+protein+machines:+preparing+the+next+generation+of+molecular+biologists.">The cell as a collection of protein machines: preparing the next generation of molecular biologists.</a> Cell. 92 (3), 291-294 (1998).</li><li>Pawson, T., Nash, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein-protein+interactions+define+specificity+in+signal+transduction.">Protein-protein interactions define specificity in signal transduction.</a> Genes Dev. 14 (9), 1027-1047 (2000).</li><li>Rual, J. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+a+proteome-scale+map+of+the+human+protein-protein+interaction+network.">Towards a proteome-scale map of the human protein-protein interaction network.</a> Nature. 437 (7062), 1173-1178 (2005).</li><li>Phizicky, E. M., Fields, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein-protein+interactions:+methods+for+detection+and+analysis.">Protein-protein interactions: methods for detection and analysis.</a> Microbiol Rev. 59 (1), 94-123 (1995).</li><li>Ho, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systematic+identification+of+protein+complexes+in+Saccharomyces+cerevisiae+by+mass+spectrometry.">Systematic identification of protein complexes in Saccharomyces cerevisiae by mass spectrometry.</a> Nature. 415 (6868), 180-183 (2002).</li><li>Krogan, N. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+landscape+of+protein+complexes+in+the+yeast+Saccharomyces+cerevisiae.">Global landscape of protein complexes in the yeast Saccharomyces cerevisiae.</a> Nature. 440 (7084), 637-643 (2006).</li><li>Wittig, I., Braun, H. P., 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=Blue+native+PAGE.">Blue native PAGE.</a> Nat Protoc. 1 (1), 418-428 (2006).</li><li>Schagger, H., Cramer, W. A., 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=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>Laemmli, U. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cleavage+of+structural+proteins+during+the+assembly+of+the+head+of+bacteriophage+T4.">Cleavage of structural proteins during the assembly of the head of bacteriophage T4.</a> Nature. 227 (5259), 680-685 (1970).</li><li>Beisiegel, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+Blotting.">Protein Blotting.</a> Electrophoresis. 7 (1), 1-18 (1986).</li><li>Killinger, B. A., Moszczynska, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+alpha-Synuclein+Multimer+Stoichiometry+in+Complex+Biological+Samples+by+Electrophoresis.">Characterization of alpha-Synuclein Multimer Stoichiometry in Complex Biological Samples by Electrophoresis.</a> Anal Chem. 88 (7), 4071-4084 (2016).</li><li>Newman, A. J., Selkoe, D., Dettmer, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+method+for+quantitative+immunoblotting+of+endogenous+alpha-synuclein.">A new method for quantitative immunoblotting of endogenous alpha-synuclein.</a> PLoS One. 8 (11), e81314 (2013).</li><li>Wong, S. 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> Chemistry of protein conjugation and cross-linking. , (1991).</li><li>Seddon, A. M., Curnow, P., Booth, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Membrane+proteins,+lipids+and+detergents:+not+just+a+soap+opera.">Membrane proteins, lipids and detergents: not just a soap opera.</a> Biochim Biophys Acta. 1666 (1-2), 105-117 (2004).</li><li>Tanford, C., Reynolds, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+membrane+proteins+in+detergent+solutions.">Characterization of membrane proteins in detergent solutions.</a> Biochim Biophys Acta. 457 (2), 133-170 (1976).</li><li>Peters, K., Richards, F. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+cross-linking:+reagents+and+problems+in+studies+of+membrane+structure.">Chemical cross-linking: reagents and problems in studies of membrane structure.</a> Annu Rev Biochem. 46, 523-551 (1977).</li><li>Lomant, A. J., Fairbanks, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+probes+of+extended+biological+structures:+synthesis+and+properties+of+the+cleavable+protein+cross-linking+reagent+[35S]dithiobis(succinimidyl+propionate).">Chemical probes of extended biological structures: synthesis and properties of the cleavable protein cross-linking reagent [35S]dithiobis(succinimidyl propionate).</a> J Mol Biol. 104 (1), 243-261 (1976).</li><li>Sun, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Crystal+structure+of+mitochondrial+respiratory+membrane+protein+complex+II.">Crystal structure of mitochondrial respiratory membrane protein complex II.</a> Cell. 121 (7), 1043-1057 (2005).</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=Native+electrophoretic+techniques+to+identify+protein-protein+interactions.">Native electrophoretic techniques to identify protein-protein interactions.</a> Proteomics. 9 (23), 5214-5223 (2009).</li></ol>

Protein-protein interactions are important for every task living things carry out. Because of this, they are the subject of intense scrutiny and research. Multimer-PAGE is a novel method for capturing, separating, and analyzing a wide range of protein complexes. We have previously demonstrated its applicability to studying oligimerization of the disease-associated protein &#945;-synuclein11. However, it is extensible to many protein complexes, as demonstrated in Figure 2. When com...

Normal cellular function is dependent on protein-protein interactions1,2. As a result, human diseases are often marked by perturbations in the assembly and behavior of various protein complexes3. The ability to characterize such interactions is therefore critical. Current means of detecting these interactions require purification of target proteins, often followed by pull-down of their interacting partners. Conventional purification is accomplished by differential centrifugation, precipitation, and/or chromatography4. These methods are time-consuming, must be altered for each target protein, and often result in low yields. Modern purification methods involve the fusion of peptide tags to target proteins, followed by immunoprecipitation or extraction on columns loaded with beads bound to a capture molecule5,6. While this is extensible to many proteins, it requires sequence modification of the target, potentially resulting in constructs that differ in affinity for their usual binding partners. The delicate nature of some protein-protein interactions means this method may not be applicable to many scenarios. Additionally, the pull-down assays used to map protein-protein interactions may not capture an accurate cellular picture, due to restricted degrees of freedom and non-native levels of the bait protein.
Ideally, protein complexes could be detected in their native states, without the need for purification or pull-down. Blue native polyacrylamide gel electrophoresis (BN-PAGE) was developed as a less-denaturing alternative to sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and allows for the separation of some proteins and complexes from biological samples7. However, proteins in BN-PAGE separate based on a large number of variables, including size, charge, three-dimensional structure, and association with other molecules. The interactions of these factors often result in co-separation of proteins, aggregate formation, and poor protein band resolution. Two-dimensional native-polyacrylamide gel electrophoresis resolves some, but not all, of these problems8.
To circumvent the complications associated with native separation, some authors use amine-reactive cross-linking reagents, such as dithiobis(succinimidyl propionate) (DSP), to capture protein complexes in tissue lysates4. These treated lysates can then be denatured and separated by SDS-PAGE, while preserving the native size and makeup of protein complexes. However, since cross-linking reagents react based on proximity of one molecule to another, and proteins in tissue lysates have many degrees of freedom and can stochastically interact, nonspecific background cross-linking can be high, especially in concentrated samples. This can lead to difficult-to-interpret results.
Here, we demonstrate the use of a hybrid BN-PAGE/SDS-PAGE method, termed multimer-polyacrylamide gel electrophoresis (multimer-PAGE), to separate and detect protein assemblies in complex mixtures. Initially, cell lysate is suspended in polyacrylamide gel via BN-PAGE. The lysate-containing gel is then reacted with the cross-linking reagent DSP. Pseudo-immobilized and slightly separated on the gel, proteins are much less likely to react nonspecifically, meaning background cross-linker reactivity is reduced. After cross-linking, the gel bands are excised and separated via SDS-PAGE. The resultant gel can then be analyzed by any means typically associated with polyacrylamide gel electrophoresis. This method allows for the separation and detection of native protein complexes in unmodified tissue lysate, without the need for additional purification or pull-down.

<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

There are many well-developed methods for purifying and studying single proteins and peptides. However, most cellular functions are carried out by networks of interacting protein complexes, which are often difficult to investigate because their binding is non-covalent and easily perturbed by purification techniques. This work describes a method of stabilizing and separating native protein complexes from unmodified tissue using two-dimensional polyacrylamide gel electrophoresis. Tissue lysate is loaded onto a non-denaturing blue-native polyacrylamide gel, then an electric current is applied until the protein migrates a short distance into the gel. The gel strip containing the migrated protein is then excised and incubated with the amine-reactive cross-linking reagent dithiobis(succinimidyl propionate), which covalently stabilizes protein complexes. The gel strip containing cross-linked complexes is then cast into a sodium dodecyl sulfate polyacrylamide gel, and the complexes are separated completely. The method relies on techniques and materials familiar to most molecular biologists, meaning it is inexpensive and easy to learn. While it is limited in its ability to adequately separate extremely large complexes, and has not been universally successful, the method was able to capture a wide variety of well-studied complexes, and is likely applicable to many systems of interest.

In this demonstration experiment, multimer-PAGE was performed on whole rat brain lysate. The resultant separated proteins were blotted onto polyvinylidene diflouride (PVDF) membranes, and then probed with antibodies against proteins that are known to form complexes. Figure 1 shows a validation of the protocol by two means. First, we demonstrate that the cross-linked proteins are cleavable by addition of a reducing agent, meaning the observed higher molecular weight specie...

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

A method for stabilizing and separating native protein complexes from unmodified tissue lysate using an amine-reactive protein cross-linker coupled to a novel two-dimensional polyacrylamide gel electrophoresis (PAGE) system is presented.

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

Research

JoVE Journal

Biochemistry

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

Sheathless Capillary ElectrophoresisÃƒÆ’Ã‚Â¢ÃƒÂ¢Ã¢â‚¬Å¡Ã‚Â¬ÃƒÂ¢Ã¢â€šÂ¬Ã…â€œMass 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 ...

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 ...

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. ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

Using In Vitro Fluorescence Resonance Energy Transfer to Study the Dynamics Of Protein Complexes at a Millisecond Time Scale

Proteins are the primary operators of biological systems, and they usually interact with other macro- or small molecules to carry out their biological ...