A probable intramembrane site-2 protease (S2P) that cleaves type-2 transmembrane proteins within their membrane-spanning domains. Regulated intramembrane proteolysis (RIP) occurs when an extracytoplasmic signal (possibly oxidative stress) triggers a concerted proteolytic cascade to transmit information and elicit cellular responses. The membrane-spanning regulatory substrate protein is first cut extracytoplasmically (site-1 protease, S1P), then within the membrane itself (site-2 protease, S2P, this entry), while cytoplasmic proteases finish degrading the regulatory protein, liberating the effector protein. Belongs to the peptidase M50B family.