protein_function: Protease inhibitor required for egg fertilization.Required to prevent premature zona pellucida hardening beforefertilization, probably by inhibiting the protease activity ofASTL, a protease that mediates the cleavage of ZP2 and triggerszona pellucida hardening (By similarity)..
Fetuin-B is a protein that in humans is encoded by the FETUB gene. It is mapped to 3q27, where the FETUA gene is localized. The protein encoded by this gene is a member of the fetuin family, part of the cystatin superfamily of cysteine protease inhibitors. Fetuins have been implicated in several diverse functions, including osteogenesis and bone resorption, regulation of the insulin and hepatocyte growth factor receptors, and response to systemic inflammation. This protein may be secreted by cells.