Saccharopepsin (IPR033819)

Short name: Saccharopepsin

Overlapping homologous superfamilies


Domain relationships


Saccharopepsin (or fungal proteinase A, MEROPS identifier A01.018) is a member of the aspartic proteinase superfamily. In Saccharomyces cerevisiae, targeted to the vacuole as a zymogen, activation of saccharopepsin at acidic pH can occur by two different pathways: a one-step process to release mature saccharopepsin, involving the intervention of proteinase B, or a step-wise pathway via the auto-activation product known as pseudo-saccharopepsin. Once active, saccharopepsin is essential to the activities of other yeast vacuolar hydrolases, including proteinase B and carboxypeptidase Y. The mature enzyme is bilobal, with each lobe providing one of the two catalytically essential aspartic acid residues in the active site. The crystal structure of free saccharopepsin shows that the flap loop is atypically pointing directly into the S(1) pocket of the enzyme. Saccharopepsin preferentially hydrolyzes hydrophobic residues such as Phe, Leu or Glu at the P1 position and Phe, Ile, Leu or Ala at P1'. Moreover, the enzyme is inhibited by IA3, a natural and highly specific inhibitor produced by S. cerevisiae [PMID: 17447722].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0004190 aspartic-type endopeptidase activity

Cellular Component

GO:0000324 fungal-type vacuole

Contributing signatures

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