PSN

Presenilin, signal peptide peptidase, family
PSN
SMART accession number:SM00730
Description: Presenilin 1 and presenilin 2 are polytopic membrane proteins, whose genes are mutated in some individuals with Alzheimer's disease. Distant homologues, present in eukaryotes and archaea, also contain conserved aspartic acid residues which are predicted to contribute to catalysis. At least one member of this family has been shown to possess signal peptide peptidase activity.
Interpro abstract (IPR006639):

Presenilin 1 (PSN1) and presenilin 2 (PSN2) are membrane proteins, whose genes are mutated in some individuals with Alzheimer's disease. They undergo tightly regulated endolytic processing to generate stable PSN C-terminal and N-terminal fragments that form the catalytic core of the gamma-secretase complex, an endoprotease complex that catalyses the intramembrane cleavage of integral membrane proteins such as Notch receptors [(PUBMED:20482315)].

Presenelins are related to the signal peptide peptidase (SPP) family of aspartic proteases that promote intramembrane proteolysis to release biologically important peptides. However, the SPPs work as single polypeptides. SPP catalyses intramembrane proteolysis of some signal peptides after they have been cleaved from a preprotein. In humans, SPP activity is required to generate signal sequence-derived human lymphocyte antigen-E epitopes that are recognised by the immune system, and are required in the processing of the hepatitis C virus core protein [(PUBMED:12077416), (PUBMED:22593157)].

This group of aspartic peptidases belong to MEROPS peptidase family A22 (presenilin family, clan AD).

GO component:integral component of membrane (GO:0016021)
GO function:aspartic-type endopeptidase activity (GO:0004190)
Family alignment:
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There are 1921 PSN domains in 1920 proteins in SMART's nrdb database.

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