Binds 1 zinc ion per subunit. Expressed in all tissues, except liver, with high expression in placenta, lung, spleen and veins. The conserved cysteine present in the cysteine-switch motif binds the catalytic zinc ion, thus inhibiting the enzyme. The dissociation of the cysteine from the zinc ion upon the activation-peptide release activates the enzyme. The precursor is cleaved by a furin endopeptidase. Disease susceptibility is associated with variants affecting the gene represented in this entry. By similarity with mouse isoform.