Orf and Hymowitz (1976) using polyacrylamide gel electrophoresis revealed that the seed protein band called "A" by Larsen and Caldwell (1968) occurs at Rf 0.36 and the seed protein band called "B" occurs at Rf 0.42 (Rf= mobility relative to a bromophenol blue dye front in a 10% polyacrylamide gel anodic system using a pH 8.3 Tris-glycine buffer). The inheritance of these proteins (although the proteins were not characterized) was reported as being controlled by two codominant alleles at a single locus (Larsen and Caldwell, 1968). Orf and Hymowitz (1976) proposed the gene symbols Sp1a and Sp1b for the electrophoretic forms that occur at Rf 0.36 and Rf 0.42, respectively.