Abstract
Circulating levels of the Ss protein of mouse serum, an antigenic homologue of human C4, are controlled by alleles within the S region of the H-2 complex. We have shown that the Ss protein can exist in at least two forms, distinguishable by electrophoresis, ion exchange chromatography and gel filtration. An electrophoretically slow form with an apparent molecular weight of approximately 160,000 by gel filtration is found in EDTA plasma and an electrophoretically faster form with an apparent molecular weight of approximately 130,000 by gel filtration is found in incubated serum. Ss protein antigen can be separated from C4 functional hemolytic activity by either ion exchange chromatography or gel filtration done under certain conditions. Because of this the functional relationship of the Ss protein and C4 were examined further. EAC142 obtained by incubating EA in mouse serum had readily demonstrable C4 function and could be agglutinated with anti-Ss antibody. These cells lost their C4 hemolytic function but not Ss agglutinability upon incubation in EDTA.
