Responsible for the proteolytic processing of the amyloid precursor protein (APP). Cleaves APP, between residues 690 and 691, leading to the generation and extracellular release of beta-cleaved soluble APP, and a corresponding cell-associated C-terminal fragment which is later released by gamma-secretase. It has also been shown that it can cleave APP between residues 671 and 672 (By similarity). Responsible also for the proteolytic processing of CLTRN in pancreatic beta cells (By similarity). Broad endopeptidase specificity. Cleaves Glu-Val-Asn-Leu-|-Asp-Ala-Glu-Phe in the Swedish variant of Alzheimer's amyloid precursor protein. Monomer. Interacts ith RTN3 and RTN4. Colocalized with CLTRN. High expression in pancreatic islets. Expressed at much lower levels in the pituitary, colon, and ovaries and is nearly absent from all the other tissues. Undergoes autoproteolytic cleavage. Glycosylated. Belongs to the peptidase A1 family.