Vitamin D-Binding Protein

Vitamin D-binding protein (VDBP) is a multifunctional protein found in plasma, ascitic fluid, cerebrospinal fluid, urine, and on the surface of many cell types. In plasma, it carries the vitamin D sterols and prevents polymerization of actin by binding its monomers. VDBP associates with membrane-bound immunoglobulin on the surface of B-lymphocytes and with IgG Fc receptor on the membranes of T-lymphocytes. Over 80 variants of human VDBP have been identified. It was initially characterized as group-specific component or Gc-globulin and its identity as the plasma vitamin D binding protein was discovered in 1975. Originating in the liver, it has a strong homology with serum albumin and a-fetoprotein. Although many thousands of sera have been tested, deletion or gross alteration of the VDBP gene has not been detected; lending support to the notion that such mutations might be lethal.

Swiss-Prot Accession Number: P02774