Biochemistry

Two by Two

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Science  26 Aug 2005:
Vol. 309, Issue 5739, pp. 1303
DOI: 10.1126/science.309.5739.1303a

Membrane proteins have never been easy to study, but two groups have applied modifications of soluble protein biochemistry to catalog protein-protein interactions in the membranes of Escherichia coli and Saccharomyces cerevisiae. Stenberg et al.use a two-dimensional (native/denaturing) electrophoretic system to identify 34 solubilized protein complexes from the bacterial inner membrane and 9 complexes from the outer membrane. Even though the complete sequence of the E. coli genome is available, the functional roles of many genes are not; the protein YhcB associates stoichiometrically with the two major subunits of cytochrome bd quinol oxidase and can now be assigned as a subunit of this enzyme. Miller et al.use the split-ubiquitin yeast two-hybrid system to enumerate almost 2000 interactions involving roughly 500 integral membrane proteins. Unlike the stable complexes isolated by detergent solubilization, this approach probably picks up transient interactions as well, and correlating the two-hybrid results with bioinformatic and experimental data led to their classification into confidence categories, of which 131 interactions were most likely to represent true positives. — GJC

J. Biol. Chem. 10.1074/jbc.M506479200 (2005); Proc. Natl. Acad. Sci. U.S.A. 102, 12123 (2005).

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