Author(s): P Vani, M Swarna, N Uma, M Kinnera, NLD Prasad, I Sudheer Babu
Human fetuin is synonymous with α 2-HS-glycoprotein (genetic symbol AHSG), α 2-HS, A2HS, AHS, HSGA, and fetuin-A. Fetuin-A exists as a single-copy gene in the human and mouse genomes. A closely related gene, fetuin-B, also exists in the human, rat, and mouse genomes. Like f etuin-A, fetuin-B is made predominantly by the live r and to a lesser extent by a number of secretary tissues. Fetuins exist in all vertebrate genomes including fish and reptiles. Fetuins aremembers of a family of proteins that evolved from the protein cystatin by gene duplication and exchange of gene segments. Fetuins thus belong to the cystatin super family of proteins. Fetuin relatives within this super family are the histidine-rich glycoprotein (HRG) and kininogen (KNG). Fetuins are blood proteins that are made in theliver and secreted into the bloodstream. They belong to a large group of binding proteins mediating the transport and availability of a wide variety of cargo substances in the bloodstream. The best known representative of these carrier proteins is serum albumin, the most abundant protein in the blood plasma of adult animals. Fetuin is more abundant in fetal blood, hence the name"fetuin" (from Latin, fetus). Fetal calf serum contains more fetuin than albumin, while adult serum contains more albuminthan fetuin.