Fetuin B is thought to have functions in female fertility, metabolism, and liver disease. A protease inhibitor belonging to the fetuin family of proteins, within the cystatin superfamily, fetuin b’s structure includes two cystatin domains (CY1 and CY2) connected by a linker, with a CPDCP-trunk and a C-terminal region (CTR) (Cuppari et al.). This plasma protein originates in the liver (Denecke et al.) and acts to inhibit the activity of ovastacin, a metalloprotease that causes the zona pellucida to harden, leading to female infertility (Karmilin et al.). Fetuin B has also been reported to increase apoptosis, and inhibit migration and invasion of prostate cancer cells, in in vitro and in vivo settings (Zhan et al.). Elevated serum fetuin B has been linked to non-alcoholic fatty liver disease (NAFLD) (Zhu et al.). This protein contains a His-residue tag at the carboxyl end of the polypeptide chain. For consistency and reproducibility across your applications, apolipoprotein H from STEMCELL comes lyophilized with ≥ 92% purity, and is verified by LAL analysis to ensure endotoxin levels are ≤ 1.0 EU/μg protein.