Signal peptidase complex subunit 2 (IPR009582)

Short name: SigPept_cplx_su2

Overlapping homologous superfamilies


Family relationships



This family consists of several microsomal signal peptidase 25 kDa subunit proteins. Translocation of polypeptide chains across the endoplasmic reticulum (ER) membrane is triggered by signal sequences. Subsequently, signal recognition particle interacts with its membrane receptor and the ribosome-bound nascent chain is targeted to the ER where it is transferred into a protein-conducting channel. At some point, a second signal sequence recognition event takes place in the membrane and translocation of the nascent chain through the membrane occurs. The signal sequence of most secretory and membrane proteins is cleaved off at this stage. Cleavage occurs by the signal peptidase complex (SPC) as soon as the lumenal domain of the translocating polypeptide is large enough to expose its cleavage site to the enzyme. The signal peptidase complex is possibly also involved in proteolytic events in the ER membrane other than the processing of the signal sequence, for example the further digestion of the cleaved signal peptide or the degradation of membrane proteins. Mammalian signal peptidase is as a complex of five different polypeptide chains [PMID: 8632014].

GO terms

Biological Process

GO:0006465 signal peptide processing

Molecular Function

GO:0008233 peptidase activity

Cellular Component

GO:0016021 integral component of membrane
GO:0005787 signal peptidase complex

Contributing signatures

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