Document Type


Publication Date


Publication Title

Proceedings of the National Academy of Sciences of the United States of America


Geisel School of Medicine


SecY, SecE, and band 1 copurify as the SecY/E integral membrane domain of Escherichia coli preprotein translocase. To measure the in vivo association of these polypeptides and assay possible exchange, plasmid-borne secY and secE genes were placed under control of the ara regulon and fused to DNA encoding the influenza hemagglutinin epitope. Cells were incubated with [35S]methionine, grown for a "chase" period, and then induced with arabinose to express epitope-tagged, nonradioactive SecY and SecE. Both the wild-type and epitope-tagged polypeptides assembled into functional, heterotrimeric SecY/E complex. However, immunoprecipitation with antibody to the epitope tag did not cross-precipitate radiolabeled SecY or SecE. Thus, these subunits normally associate stably in vivo.

Original Citation

Joly JC, Leonard MR, Wickner WT. Subunit dynamics in Escherichia coli preprotein translocase. Proc Natl Acad Sci U S A. 1994;91(11):4703-4707. doi:10.1073/pnas.91.11.4703