Fetuin A [H4]

Fetuin A, also known as a-2-z-globulin or a-2-HS-glycoprotein (A2HS), is produced by liver and secreted to plasma, selectively concentrated in bone matrix. It is expressed in hepatocytes, monocyte/macrophages and in bone and is down-regulated during injury and inflammation. Fetuin preferentially binds to and carries calcium and barium ions in the blood, where it is thought to mediate serum calcium homeostasis and mineralization, and to potentially participate in the transport of bioactive molecules. It is synthesized as a precursor and processed to generate 2 chains that are held together by a disulfide bond. It is a systemically acting calcification inhibitor. Reduced level of fetuin A in serum is associated with increased cardiovascular mortality in dialysis patients. Fetuin A can inhibit insulin-induced tyrosine phosphorylation of the insulin receptor tyrosine kinase and insulin receptor substrate-1. Fetuin A deficient mice show high insulin sensitivity and high levels of serum fetuin A are associated with insulin resistance in humans.