THE PRESENCE OF SUBUNITS IN THE INHERITED GROUP-SPECIFIC PROTEIN OF HUMAN SERUM

Abstract

Evidence for the existence of subunits in the inherited group-specific protein of human serum is presented. The possibility of subunlts within the Gc molecule was 1st raised by the electrophoretic heterogeneity observed in purified Gc 1-1 and Gc 2-2 in starch gel electrophoresls. The finding of Gc peptlde patterns containing one half the expected number of tryptic peptides strongly supports this possibility. Reduction of the Gc molecule resulted in a decrease in the molecular weight of the Gc protein as judged by gel filtration. Analytical ultracentrifugation analyses of the reduced Gc protein confirmed the presence of subunlts, each having a molecular weight of 25,000. The results presented here suggest that the primary structure of the Gc molecule is controlled by more than 1 structural gene.