Title: Band 1 subunit of Escherichia coli preportein translocase and integral membrane export factor P12 are the same protein. | Journal: The Journal of biological chemistry. 1994 Jul;269(29):18705-7 | Authors: Douville K, Leonard M, Brundage L, Nishiyama K, Tokuda H, Mizushima S, Wickner W. | Abstract: Escherichia coli preprotein translocase consists of the peripheral membrane protein SecA and the integral membrane domain SecY/E. SecY/E, whether isolated chromatographically or by immunoprecipitation, was found to be complex of three polypeptides, SecY, SecE, and band 1. Band 1 did not correspond to a known sec gene product. The independent purification of the separate integral membrane polypeptides needed for reconstitution of translocation yielded SecY, SecE, and a protein that we termed P12. Based on the sequence of P12, we have prepared antisera to a carboxyl-terminal peptide domain and shown that this antiserum specifically labels only P12 on immunoblots of inner membrane vesicles. We now report that affinity-purified anti-P12 antibodies specifically label the band 1 subunit of the SecY/E complex, whether the SecY/E was isolated chromatographically or by precipitation with antibodies to an epitope-tagged SecY subunit. In addition, the antiserum to P12 can specifically immunoprecipitate the full three-subunit SecY/E complex from detergent extracts. This finding completes the identification of the polypeptides that are essential for catalysis of preprotein translocation. | See full PubMed entry: http://www.ncbi.nlm.nih.gov/pubmed/8034620 |
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