A previously described serum protein polymorphism in the rat identified as Gc ('vitamin D-binding protein').

The previously published serum protein polymorphisms G1-1 (Moutier, Toyama & Charrier, 1973) and 'tf' (Bender & Günther, 1978) are identical and represent genetic variation at the locus of the vitamin D-binding a-globulin, also known a Gc or group-specific component. The identity was established by comparative protein staining, by functional tests with 14C-vitamin D3, by immunological studies with specific anti-Gc sera and by the strain distribution patterns. The Gc polymorphism in the rat may initiate interesting physiological and genetical studies.