Aminopeptidase A/ENPEP: Proteins and Enzymes

The human ENPEP gene encodes aminopeptidase A (APA), which is also known as glutamyl aminopeptidase (EAP), aspartate aminopeptidase, angiotensinase A, Ca²⁺-activated glutamate aminopeptidase, membrane aminopeptidase II and the BP-1/6C3 antigen. The various names reflect its substrate specificity (prefer Glu or Asp and angiotensin II as one of the physiological substrates), Ca²⁺-dependence, cellular location (type II membrane protein) and immunological reactivity to antibody BP-1/6C3.

The deduced amino acid sequence of human ENPEP consists of a short cytoplasmic tail (residues 1 to 17), a transmembrane region (residues 18 to 40), and a long ectodomain (residues 41 to 957). In addition to the N-terminal zinc metalloprotease domain, the ectodomain of aminopeptidase A also contains the C-terminal region, which functions as an intramolecular chaperone required for the correct folding, cell surface expression and activity.