Primary structural evidence that the H-2Dq region encodes at least three distinct gene products: Dq, Lq, and Rq.

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Abstract
Class I gene products, D, L and R encoded by the D region of the H-2q haplotype were isolated by sequential immunoprecipitation from Nonidet P-40 extracts of B10.AKM murine spleen cells. Primary structural comparisons of these molecules were made by tryptic peptide map analyses and radiochemical amino acid sequence determinations. Partial NH2-terminal radiosequence analyses of the peptides generated by CNBr cleavage of these 3 molecules defined the Rq molecule as a gene product that is distinct from the Dq and Lq molecules. Comparative tryptic peptide map analyses of [3H]Arg-, [3H]Lys-, or [3H]mannose-labeled molecules were performed to determine if the Dq and Lq molecules could be distinguished. The 2 molecules were identical in their [3H]Lys-labeled peptides (17 in common) and [3H]mannose-labeled glycopeptides but could be differentiated by their [3H]Arg-labeled peptides (18 of 21 in common). These results suggest an amino acid sequence homology of 99% or greater between the Dq and Lq molecules. Structural evidence is provided for 3 D region gene products, suggesting that their antigenic differences are not due to post-translational glycosylation differences. The D region of the H-2q haplotype may provide an example of a relatively recent class I gene duplication, indicating that these genes are in a dynamic state of evolution through expansion or contraction of the gene pool.