Structure of murine Ia antigens. Two-dimensional electrophoretic analyses and high-pressure liquid chromatography tryptic peptide maps of products of the I-A and I-E subregions and of an associated invariant polypeptide

We demonstrate that an invariant polypeptide, first described by Jones et al. (21), co-immunoprecipitates with our Ia molecules, that its interaction with Ia polypeptides varies with haplotype, and that it is not a precursor of the Aα, Aβ, Eα, or Eβ polypeptides. We also show that the polypeptides that we have previously characterized are contaminated with very little, if any, invariant protein. Further, we have used = our high-pressure liquid chromatography tryptic peptide map technique to formally map the genes encoding Aα, Aβ, and Eβ to the I-A subregion using recombinant and F ₁ hybrid mice.