Phylogenetic Insight into Evolution of Mammalian Fc Fragment of γG Globulin Using Staphylococcal Protein A

Abstract

The reaction between protein A of staphylococci and the Fc portion of γG globulins has been studied using representative sera and isolated γ globulins from species representing seven classes and 30 orders of living vertebrates. No reactions with immunoglobulins derived from either the primitive or later evolving fishes were noted. No reactions were recorded among Amphibia and Reptilia as well as all birds tested, except with serum from the primitive flightless bird Rhea americana. All members of the class Mammalia, including egg-laying monotremes, showed reactions with protein A except for the American oppossum. A comparison of patterns of reactivity between protein A and isolated human rheumatoid factors showed that in the majority of instances different specificities were involved. Protein A may provide a useful tool in the study of the evolution of γG globulin.