A site-2 regulated intramembrane protease (S2P) that cleaves type-2 transmembrane proteins within their membrane-spanning domains; its endogenous substrate is unknown. Regulated intramembrane proteolysis (RIP) occurs when an extracytoplasmic signal triggers a concerted proteolytic cascade to transmit information and elicit cellular responses. A membrane-spanning regulatory substrate protein is first cut extracytoplasmically (site-1 protease, S1P), then within the membrane itself (site-2 protease, S2P, this enzyme), while cytoplasmic proteases finish degrading the regulatory protein, liberating the effector protein. Possible signals, S1P and substrates are unknown in this organism. Binds 1 zinc ion per subunit. Inhibited by 1,10-phenanthroline. Monomer. Belongs to the peptidase M50B family.