Riboflavin-binding protein. Concentration and fractional saturation in chicken eggs as a function of dietary riboflavin.
The concentration of riboflavin and riboflavin-binding protein were determined in the plasma, egg yolk and albumen from hens fed a riboflavin-deficient diet (1.2 mg/kg) supplemented with 0, 1, 2, 3, 10 and 40 mg of riboflavin/kg. We observed that the deposition of riboflavin in egg yolk and albumen is dependent on dietary riboflavin and reaches half-maximal values at about 2 mg of supplemental riboflavin/kg. The maximal amount of riboflavin deposited in the yolk is limited stoichiometrically by the amount of riboflavin-binding protein, whereas the maximum amount of riboflavin deposited in albumen is limited by other factors before saturation occurs. The amount of riboflavin-binding protein in yolk and albumen is independent of dietary riboflavin. If there is a specific oocyte receptor for riboflavin-binding protein, it cannot distinguish between the apo and holo forms of the protein. Riboflavin-binding protein is about six times more concentrated in yolk than in plasma.
D000818:Animals; D002352:Carrier Proteins / Q000097:blood / Q000378:metabolism*; D002645:Chickens; D004032:Diet; D004527:Egg Proteins / Q000097:blood / Q000378:metabolism*; D005260:Female; D026901:Membrane Transport Proteins; D010047:Ovalbumin / Q000378:metabolism; D010063:Ovum / Q000378:metabolism*; D012256:Riboflavin / Q000097:blood / Q000378:metabolism*
D002352:Carrier Proteins; D004527:Egg Proteins; D026901:Membrane Transport Proteins; C019079:riboflavin-binding protein; D010047:Ovalbumin; D012256:Riboflavin