Localization of two genetic factors to different areas of gamma-globulin molecules.

Gm(a) and Gm(b) factors are present in 7S gamma-globulin molecules and absent in 19S gamma-globulins, beta(2A)-globulins and Bence-Jones proteins, whereas the Inv(b) factor was demonstrated in all four kinds of proteins. The Inv type was identical in isolated 7S and 19S gamma-globulins of six normal sera. After papain splitting of 7S gamma-globulin, Gm determining sites were present only in the fast (F) split product and Inv determining sites were present only in the slow (S).