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. Belongs to the peptidase M1 family.