Variable synthesis and expression of E β and A e (E β ) Ia polypeptide chains in mice of differentH-2 haplotypes

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Abstract
The genetic and molecular requirements for cell-surface expression of Ia antigens precipitated by anti-I-E subregion sera have been examined. Inbred mice of thed, k, p, andr haplotypes synthesize and express on their lymphocytes the two I-region products normally found in anti-I-E-subregion immunoprecipitates, E α and Ae (E β ). Cells from mice of theb ands haplotypes fail to synthesize E α chains but do synthesize Ae chains, which remain in the cytoplasm as partially glycosylated precursors. Cells of thef andq haplotypes fail to synthesize either the Ae or E α polypeptide chains, as shown by both genetic complementation tests and analyses of total cell proteins by two-dimensional polyacrylamide gel electrophoresis. The patterns of expression of the intact E α :Ae complex are consistent with the theory that both the Ae and E α polypeptide chains must be present in the cells for either chain to be expressed in normal amounts on the cell surface. The implications of these observations for the genetics ofI-region-controlled functions are discussed.