SecG

• PFAM accession number: PF03840
• Interpro abstract (IPR004692):

  Secretion across the inner membrane in some Gram-negative bacteria occurs via the preprotein translocase pathway. Proteins are produced in the cytoplasm as precursors, and require a chaperone subunit to direct them to the translocase component [ (PUBMED:2202721) ]. From there, the mature proteins are either targeted to the outer membrane, or remain as periplasmic proteins. The translocase protein subunits are encoded on the bacterial chromosome.

  The translocase itself comprises 7 proteins, including a chaperone protein (SecB), an ATPase (SecA), an integral membrane complex (SecCY, SecE and SecG), and two additional membrane proteins that promote the release of the mature peptide into the periplasm (SecD and SecF) [ (PUBMED:2202721) ]. The chaperone protein SecB [ (PUBMED:11336818) ] is a highly acidic homotetrameric protein that exists as a "dimer of dimers" in the bacterial cytoplasm. SecB maintains preproteins in an unfolded state after translation, and targets these to the peripheral membrane protein ATPase SecA for secretion [ (PUBMED:10418149) ]. Together with SecY and SecG, SecE forms a multimeric channel through which preproteins are translocated, using both proton motive forces and ATP-driven secretion. The latter is mediated by SecA.

  SecG has two transmembrane domains, both of which contribute to the recognition of preprotein signal sequences by the translocation complex [ (PUBMED:7650029) ]. The protein also undergoes membrane topology inversion when coupled to the SecA cycle [ (PUBMED:11445571) ].

• GO process: protein secretion (GO:0009306)
• GO component: integral component of membrane (GO:0016021)
• GO function: P-P-bond-hydrolysis-driven protein transmembrane transporter activity (GO:0015450)

This is a PFAM domain. For full annotation and more information, please see the PFAM entry SecG