Isolation and characterization of a cDNA clone for the murine I-E beta polypeptide chain.

The Ia antigens, encoded within the I region of the major histocompatibility complex, are a group of cell surface glycoproteins that are involved in the control of immune responsiveness. We isolated and determined the sequence of a 1,045-base-pair cDNA clone for one of the murine immune response genes, Ek beta. Comparison of the predicted amino acid sequence of the product of Ek beta with that of Ed beta shows that most of the amino acid differences are clustered in short stretches of peptide sequence in the first external protein domain. This clustering of allelic variation suggests that observed haplotype-specific immune responsiveness to certain antigens may be controlled, at least in part, by differences in configuration defined by these regions of allelic variability in the NH2-terminal domain of the E beta chain.