Two subclasses of mouse 7S γ2-globulins are identified, and are designated γ2a- and γ2b-globulins. They are distinguished from 7S γ1-globulins, γ1A (ß2A)-globulins, and γ1M-globulins of mouse serum. Antibody activity was detected among the γ2a-globulins and γ2b-globulins of hyperimmune mouse serum.
γ2a- and γ2b-myeloma proteins were identified. The genetically determined isoantigen, Iga-1, was present on γ2a-myeloma proteins, but not on γ2b-myeloma proteins.
These findings indicate a complexity among the 7S γ2-globulins which must be taken into account in structural, functional, and genetic studies of immunoglobulins.