Evidence for 15 genetically determined electrophoretic variants of transcobalamin II in rabbit serum.

By starch gel electrophoresis and autoradiography two classes of vitamin B12 binding proteins were detected in rabbit serum. By analogy to the nomenclature used in man, the two classes of proteins were named "transcobalamin I" (TCI) and "transcobalamin II" (TCII). Fifteen TCII phenotypes were observed, and family data indicated that they are controlled by five allelic codominant genes. The possibility that the five genes arise from the action of at least two polymorphic and closely linked structural loci is discussed.