Relation between Gm(f) and the Structure of the γ-Globulin Molecule

Abstract

THE serologically detectable genetically determined antigens Gm(a) and Gm(b) are restricted to the F_c (fast) fragment of the A (Heavy) polypeptide chains of human gamma_G-globulin¹. In contrast, Gm(b^w) is present in the F_ab, (slow) fragment, and its serological activity seems to depend on the ‘quaternary’ structure of the intact gamma_G-molecule². Gm(f) activity also is localized to the F_ab fragment of gamma_G-globulin^3,4, and is also present in the 5S product obtained by pepsin digestion of the 7S gamma_G-molecule⁴ (Table 1); Gm(a) and Gm(b) activities are lost during pepsin digestion. Recent studies⁵ indicate that Gm(f) and Gm(b^w) are similar but not identical. We report here the results of experiments with anti-Gm(f) and isolated A and B chains of gamma_G-globulin.