Protein translocase subunit SecA (IPR000185)

Short name: SecA

Overlapping homologous superfamilies

Family relationships


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 [PMID: 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) [PMID: 2202721]. The chaperone protein SecB [PMID: 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 [PMID: 10418149].

SecA is a cytoplasmic protein of 800 to 960 amino acid residues. Homologues of secA are also encoded in the chloroplast genome of some algae [PMID: 8437571] as well as in the nuclear genome of plants [PMID: 7758587]. It could be involved in the intraorganellar protein transport into thylakoids.

GO terms

Biological Process

GO:0006886 intracellular protein transport
GO:0006605 protein targeting

Molecular Function

GO:0005524 ATP binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.