Structural evidence that the small subunit found associated with the TL antigen is beta 2-microglobulin.

Comparative tryptic peptide mapping and partial amino-terminal primary sequence analysis of the light chain component associated with the TL antigens showed that the small subunit of TL was identical to the beta 2m light chain associated with the H-2K or D product of the same strain. Peptide comparison of the beta 2m from the Tla products of an A strain X-ray induced leukemia RADA1 (Tlaa) and of a C57BL/6 strain X-ray induced leukemia ERLD (Tlab) showed differences to the extent of 25-35% in their peptides. This is consistent with previous results showing beta 2m allelic variations between these mouse strains. The data prove the structural identity of the beta 2m molecules from TL and H-2K, D antigens as well as reveal the strain specific polymorphism of the beta 2m associated with these products.