Plasma Vitamin D-binding Protein (Gc-globulin): Multiple Tasks

J Steroid Biochem Mol Biol. 1995 Jun;53(1-6):579-82. doi: 10.1016/0960-0760(95)00104-8.

Abstract

The transporter of vitamin D and its metabolites in blood has received increasing attention in recent years, and is recognized to be a member of a gene family that includes albumin and alpha-fetoprotein. Identical to the group specific component (Gc-globulin) of serum, the protein is a single-chain polypeptide constitutively synthesized in liver that circulates in amounts in far excess of normal vitamin D metabolite concentrations in blood. It plays the major role in the egress of endogenously synthesized vitamin D, from skin and appears to restrain D-sterols from too rapid/excessive cell entry. Along with plasma gelsolin, it comprises the plasma actin-scavenger system that facilitates removal of actin, liberated from lysed cells, by depolymerization and prevention of polymerization. Recently, the protein has been shown to behave as a co-chemotaxin specific for the complement peptide C5a, and its sialic acid-free form has been reported to play a role in macrophage activation. The latter functions strongly implicate its participation in inflammation responses. A unifying hypothesis might also suggest the protein to provide focal D-sterol delivery to cells that are important to the resolution of tissue injuries.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Actins / metabolism
  • Animals
  • Cell Compartmentation
  • Humans
  • Microfilament Proteins / metabolism
  • Tissue Distribution
  • Vitamin D / physiology*
  • Vitamin D-Binding Protein / physiology*

Substances

  • Actins
  • Microfilament Proteins
  • Vitamin D-Binding Protein
  • Vitamin D