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 (PubMed:10591213, PubMed:11083922, PubMed:11423558, PubMed:15857888, PubMed:16816112). Involved in the proteolytic shedding of PMEL at early stages of melanosome biogenesis. Cleaves PMEL within the M-beta fragment to release the amyloidogenic PMEL luminal fragment containing M-alpha and a small portion of M-beta N-terminus. This is a prerequisite step for subsequent processing and assembly of PMEL fibrils into amyloid sheets (PubMed:23754390). Responsible also for the proteolytic processing of CLTRN in pancreatic beta cells (PubMed:21907142). {ECO:0000269|PubMed:10591213, ECO:0000269|PubMed:11083922, ECO:0000269|PubMed:11423558, ECO:0000269|PubMed:15857888, ECO:0000269|PubMed:16816112, ECO:0000269|PubMed:21907142, ECO:0000269|PubMed:23754390}. This is the function of BACE2 (beta-secretase 2, Ensembl gene identifier ENSG00000182240).