Vitamins binding proteins

Milk contains specific binding proteins for retinol (vitamin A), vitamin D, riboflavin (vitamin Bj), folate and cyanocobalamin (vitamin Bi2)- Such proteins may improve the absorption of these vitamins by protecting and transferring them to receptor proteins in the intestine, or they may have antibacterial activity by rendering vitamins required by intestinal bacteria unavailable. The activity of these proteins is reduced or destroyed by heat treatments. 

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The vitamin B12 receptor which facilitates uptake of the vitamin-intrinsic factor vitamin-binding protein complex has been used to enhance oral delivery and gastrointestinal uptake of peptides and proteins as their vitamin B12 conjugates (37). Commercial efforts are under way to exploit this receptor as well as the fetal Pc receptor which facilitates intestinal uptake of antibodies from colostrum/milk (38) and the polymeric immunoglobulin receptor which facilitates the serosal to mucosal transport of IgA and IgM (39). 

The lipids of the diet include TGs, phospholipids, cholesteryl esters, cholesterol, and the fat-scivble vitamins. These nutrients require special types of biochemical machinery to facilitate their assimilation and distributicrt within the body. The biochemical apparatus used includes bile salts, apolipoprotcins, serum albumin, and vitamin-binding proteins. Apolipopnoteins are the primary subject of this section. The term apolipoprotain is used when referrmg only to the protein, whereas the term lipoprotein refers to the complex of apolipoprotein and lipid. 

Relation of Vitamin Binding Proteins to Other Transcription Factors... 

White, H.B. (1987). Vitamin-binding proteins in the nutrition of the avian embryo. J. Exp. Zool, SuppL 1, 53-63. 

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