Avian riboflavinuria IX. Qualitative action of a mutant gene in chicken on riboflavin-binding protein synthesis.

Laying chickens normally produce a riboflavin-binding protein (RBP) essential for the transfer of vitamin B2 to the egg. A mutant line of chickens (rdrd) is incapable of synthesizing functional RBP. The rdrd laying hens contain a component in the liver and the magnum of the oviduct which cross-reacts with rabbit antiserum specific for RBP. No crossreacting material (CRM) was observed in eggs or blood of rdrd hens. CRM is absent in extracts of livers of rdrd males, but it can be induced in roosters of this genotype by estradiol. CRM appears to be less immunogenic on a weight basis than RBP, and it carries less net negative charge. No measurable riboflavin-binding capacity was found for newly isolated or degraded CRM.