Metalloprotease which in vitro specifically cleaves IGFBP-2 to -6, insulin, and extracellular matrix proteins but not IGFBP-1 or IGF-II. Shows a preference for substrates with an arginine in the P1' position, the first position downstream of the scissile bond. Binds 2 calcium ions per subunit. Binds 1 zinc ion per subunit. Inhibited by EDTA, excess zinc, and also significantly by batimastat in vitro. Is not inhibited by other metalloprotease inhibitors like phosphoramidon, captopril and galardine or those targeting other classes of proteases. Optimum pH is 7.5. Monomer. Consists of two subdomains separated by an active site cleft containing the catalytic zinc ion. The inactive zymogen pro-ulilysin undergoes calcium-mediated autolytic activation to the mature ulilysin. Autoproteolytic activation entails removal of the first 60 residues and of a highly charged 20-residue C-terminal tail. Belongs to the peptidase M43B family.