May play a role in the adhesive and proteolytic events that occur during lymphocyte emigration or may function in ectodomain shedding of lymphocyte surface target proteins, such as FASL and CD40L. May be involved in sperm maturation. Binds 1 zinc ion per subunit. Expressed predominantly in secondary lymphoid tissues, such as lymph node, spleen, small intestine, stomach, colon, appendix and trachea. The lymphocyte population is responsible for expression of this protein in these tissues. Isoform 2 is expressed preferentially in spleen. 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. Pro-domain removal and maturation may be, at least in part, autocatalytic.