DNA sequence and characterization of human class II major histocompatibility complex beta chains from the DR1 haplotype.
Bell JI., Estess P., St John T., Saiki R., Watling DL., Erlich HA., McDevitt HO.
Two HLA class II beta-chain clones from a cell line homozygous for the DR1 haplotype have been characterized and sequenced. They represent a DR beta chain (2918.4) and a DQ beta chain (2918.8). Clone 2918.4 has been used to select mRNA from a lymphoblastoid cell line, and this was injected into Xenopus oocytes with mRNA selected with a DR alpha chain. The translation products were immunoprecipitated with a beta-chain-specific monoclonal antibody and electrophoresed on two-dimensional gels. This revealed positive signals in the positions predicted for beta and alpha chains. Sequence comparisons of 2918.4 with previously published DR beta-chain sequences confirm the presence of two regions of variability in the membrane distal domain. Analysis of the sequence of 2918.8 identified it as a DQ beta chain identical to one previously published from a DR3,w6 cell line. We speculate, therefore, that the DQ beta sequence represents the DQ1 specificity shared by the DR1 and DRw6 haplotypes.