Dependence of a Gm(b) Antigen on the Quaternary Structure of Human Gamma Globulin

The antigens associated with the Gm(b) factor of human 7S gamma-globulin differ in Caucasoids and Negroids. The studies reported here show that an antigen, Gm(b(w)), associated with the Gm(b) of whites but not with that of Negroes, is present on the S (slow) fragment of 7S gamma-globulin obtained by digestion with papain or pepsin. All other Gm antigens thus far studied have been found on the F (fast) fragment. The antigens Inv(a) and Inv(b) were detected on isolated L-chains, and Gm(a) and Gm(b) were detected on isolated H-chains, but Gm(b(w)) was detected on neither. Recombining the H- and L-chains restored activity for Gm(b(w)) comparable to that of intact gamma-globulin