|Protein Name||Vitamin D-binding protein|
|Ref Sequence Id||NP_001030457.1|
|Amino Acid Lenth||474|
|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|
|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. |
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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.
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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.