Lipid, detergent, and Coomassie Blue G-250 affect the migration of small membrane proteins in blue native gels: mitochondrial carriers migrate as monomers not dimers.

TitleLipid, detergent, and Coomassie Blue G-250 affect the migration of small membrane proteins in blue native gels: mitochondrial carriers migrate as monomers not dimers.
Publication TypeJournal Article
Year of Publication2013
AuthorsCrichton, PG, Harding, M, Ruprecht, JJ, Lee, Y, Kunji, ERS
JournalJ Biol Chem
Volume288
Issue30
Pagination22163-73
Date Published2013 Jul 26
ISSN1083-351X
KeywordsBlotting, Western, Detergents, Electrophoresis, Polyacrylamide Gel, Lipids, Mitochondrial ADP, ATP Translocases, Molecular Weight, Protein Multimerization, Rosaniline Dyes, Saccharomyces cerevisiae Proteins
Abstract

Blue native gel electrophoresis is a popular method for the determination of the oligomeric state of membrane proteins. Studies using this technique have reported that mitochondrial carriers are dimeric (composed of two ∼32-kDa monomers) and, in some cases, can form physiologically relevant associations with other proteins. Here, we have scrutinized the behavior of the yeast mitochondrial ADP/ATP carrier AAC3 in blue native gels. We find that the apparent mass of AAC3 varies in a detergent- and lipid-dependent manner (from ∼60 to ∼130 kDa) that is not related to changes in the oligomeric state of the protein, but reflects differences in the associated detergent-lipid micelle and Coomassie Blue G-250 used in this technique. Higher oligomeric state species are only observed under less favorable solubilization conditions, consistent with aggregation of the protein. Calibration with an artificial covalent AAC3 dimer indicates that the mass observed for solubilized AAC3 and other mitochondrial carriers corresponds to a monomer. Size exclusion chromatography of purified AAC3 in dodecyl maltoside under blue native gel-like conditions shows that the mass of the monomer is ∼120 kDa, but appears smaller on gels (∼60 kDa) due to the unusually high amount of bound negatively charged dye, which increases the electrophoretic mobility of the protein-detergent-dye micelle complex. Our results show that bound lipid, detergent, and Coomassie stain alter the behavior of mitochondrial carriers on gels, which is likely to be true for other small membrane proteins where the associated lipid-detergent micelle is large when compared with the mass of the protein.

DOI10.1074/jbc.M113.484329
Alternate JournalJ. Biol. Chem.
Citation Key10.1074/jbc.M113.484329
PubMed ID23744064
PubMed Central IDPMC3724668
Grant ListMC_U105663139 / / Medical Research Council / United Kingdom
/ / Medical Research Council / United Kingdom