|Protein Name||Vitamin D-binding protein|
|Ref Sequence ID||NP_001030457.1|
|Protein Existence Status||Reviewed: Experimental evidence at transcript level|
|Presence in other biological fluids/tissue/cells||Serum,|
|Protein Function||Role in the transport of vitamin D metabolites; maintains total levels of vitamin D and regulates the amounts of free (unbound) vitamin D available for specific tissues and cell types to utilize; binds actin and fatty acids preventing their polymerization; immune functions such as in B-cells, DBP seems to participate in the linkage of surface immunoglobulins|
|Biochemical Properties||Associated and copurified with actin; existence of three major polymorphic forms -GC1F, GC1S and GC2; most DBP circulates without any vitamin D ligands attached; DBP binds actin with an affinity of 1 109 M^(–1) and fatty acids with reported affinity of 6–7 105 M(^–1)|
|Significance in milk||Colostrum could be a rich source of vitamin D associated with DBP and could play an important role in the intake of vitamin D sterols in the newborn.|
|PTMs||Glycosylated; GC1 forms have glycosylations at positions 418 and 420, whereas GC2 has glycosylation only at 418; trisaccharides as most frequent in GC1 with lesser amounts of disaccharides as found in humans|
| Site(s) of PTM(s) |
|Predicted Disorder Regions||17-28,107-127|
|TM Helix Prediction||No TM helices|
|Bibliography||1. Ena, J., Pérez, M. D., Aranda, P., Sánchez, L., and Calvo, M. (1992) Presence and changes in the concentration of vitamin D-binding protein throughout early lactation in human and bovine colostrum and milk. J. Nutr. Biochem. 3, 498–502. |
2. HIRSCHFELD, J. (1959) Immune-electrophoretic demonstration of qualitative differences in human sera and their relation to the haptoglobins. Acta Pathol. Microbiol. Scand. 47, 160–168.
3. Svasti, J., Kurosky, A., Bennett, A., and Bowman, B. H. (1979) Molecular basis for the three major forms of human serum vitamin D binding protein (group-specific component). Biochemistry 18, 1611–1617.
4. Cooke, N. E. and David, E. V. (1985) Serum vitamin D-binding protein is a third member of the albumin and alpha fetoprotein gene family. J. Clin. Invest. 76, 2420–2424.
5. Svasti, J. and Bowman, B. H. (1978) Human group-specific component. Changes in electrophoretic mobility resulting from vitamin D binding and from neuraminidase digestion. J. Biol. Chem. 253, 4188–4194.
6. Ravnsborg, T., Olsen, D. T., Thysen, A. H., Christiansen, M., Houen, G., and Højrup, P. (2010) The glycosylation and characterization of the candidate Gc macrophage activating factor. Biochim. Biophys. Acta 1804, 909–917.
7. Mc Leod, J. F., Kowalski, M. A., and Haddad, J. G. (1989) Interactions among serum vitamin D binding protein, monomeric actin, profilin, and profilactin. J. Biol. Chem. 264, 1260–1267.
8. Calvo, M. and Ena, J. M. (1989) Relations between vitamin D and fatty acid binding properties of vitamin D-binding protein. Biochem. Biophys. Res. Commun. 163, 14–17.