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. 1997 Sep;179(18):5699–5704. doi: 10.1128/jb.179.18.5699-5704.1997

In vivo cross-linking of the SecA and SecY subunits of the Escherichia coli preprotein translocase.

E H Manting 1, C van der Does 1, A J Driessen 1
PMCID: PMC179456  PMID: 9294424

Abstract

Precursor protein translocation across the Escherichia coli inner membrane is mediated by the translocase, which is composed of a heterotrimeric integral membrane protein complex with SecY, SecE, and SecG as subunits and peripherally bound SecA. Cross-linking experiments were conducted to study which proteins are associated with SecA in vivo. Formaldehyde treatment of intact cells results in the specific cross-linking of SecA to SecY. Concurrently with the increased membrane association of SecA, an elevated amount of cross-linked product was obtained in cells harboring overproduced SecYEG complex. Cross-linked SecA copurified with hexahistidine-tagged SecY and not with SecE. The data indicate that SecA and SecY coexist as a stable complex in the cytoplasmic membrane in vivo.

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Selected References

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