Regulates central hypertension through its calcium-modulated preference to cleave N-terminal acidic residues from peptides such as angiotensin II. Release of N-terminal glutamate (and to a lesser extent aspartate) from a peptide. Binds 1 zinc ion per subunit. Substrate specificity is modulated by calcium which enhances the enzymatic activity for cleavage of acidic residues while reducing its activity with basic residues. Inhibited by aminopeptidase inhibitors amastatin and bestatin. Homodimer; disulfide-linked. Expressed in choriocarcinoma cancer cell lines (at protein level) (PubMed:10692253). Expressed by epithelial cells of the proximal tubule cells and the glomerulus of the nephron. Also found in a variety of other tissues. Belongs to the peptidase M1 family.