| Modification Notes |
The cathepsin family of proteolytic enzymes include several diverse classes of proteases. Cathepsins B, L, H, K, S and O comprise the cysteine protease class (1). Cathepsins D and E comprise the aspartyle protease class (2). The serine protease class includes cathepsin G (3). Cathepsins function in cellular metabolism and participate in peptide biosynthesis and protein degradation. Cathepsin A, a serine carboxypeptidase, exists in a high molecular weight lysosomal complex with b-galactosidase (b-gal) and a-neuraminidase (Neu1) (4). Cathepsin A functions to protect b-gal and Neu1 from intralysosomal proteolysis (4). Deficiencies in cathepsin A lead to deficiencies in b-gal and Neu1 (4). The gene encoding human cathepsin A maps to chromosome 20q13.12 (5). Mutations in this gene cause glactosialidosis, a lysosomal storage disorder resulting from the b-gal and Neu1 deficiencies (4). |