Acting on peptide bonds (peptidases);
Preferential cleavage at Gly-Ser-Arg373! of glycoprotein gp43 in Xenopus laevis coelemic egg envelope to yield gp41
The egg envelope of the South African clawed frog (Xenopus laevis) is modified during transit of the egg through the pars rectus oviduct, changing the egg envelope from an unfertilizable form to a fertilizable form. This process involves the conversion of glycoprotein gp43 to gp41 (ZPC) by the pars recta protease oviductin. It is thought that the enzymically active protease molecule comprises the N-terminal protease domain coupled to two C-terminal CUB domains, which are related to the mammalian spermadhesin molecules implicated in mediating sperm-envelope interactions . The enzyme is also found in the Japanese toad (Bufo japonicus) . Belongs in peptidase family S1.
Oviductin, the Xenopus laevis oviductal protease that processes egg envelope glycoprotein gp43, increases sperm binding to envelopes, and is translated as part of an unusual mosaic protein composed of two protease and several CUB domains.