Localization of the xg allotypic determinants,in which carbohydrate structures take part,to the separable parts of the rabbit IgG molecule

Enzyme-immunologic and radio-immunologic techniques made it possible to localize the determinants responsible for the xg allotypic specificity (in which carbohydrate structures are involved) to the heavy polypeptide chains and the Fc fragment of rabbit IgG, but not to the light chains nor the Fab fragment, and in part to the F(ab′)2 fragment obtained by pepsin digestion. The relationship between the xg and the e14 allotypic patterns, to date always found together in the same individuals, is discussed in light of these results.