title: Analysis of DR beta and DQ beta chain cDNA clones from a DR7 haplotype.
abstract: A cDNA library was constructed from a DR7, DRw53, DQw2 homozygous cell line, cDNA clones corresponding to DR beta and DQ beta chains were isolated, and the nucleotide sequences of the polymorphic first domains of these chains were determined. A novel screening strategy allowed rapid and simple identification of cDNA clones corresponding to both DR beta chains (DR7 beta1 and DR7 beta2): DR7 beta2 clones have a recognition site for the enzyme BssHII, whereas DR7 beta1 clones do not. The DR7 beta 1 sequence differs significantly from all previously described DR beta chains. As predicted by the presence of the BssHII site in DR7 beta 2 clones, the DR7 beta 2 sequence differs from the DR7 beta 1 sequence. The sequence of the DRw53-associated DR7 beta 2 chain is identical to the reported sequence of the DRw53-associated DR4 beta 2 chain. In addition, the sequence of the DQ beta chain from the DR7, DQw2 cell line is identical to the reported sequence of a DQ beta chain from a DR3, DQw2 cell. These findings raise interesting questions about the evolution of the DR3, DR4, and DR7 haplotypes.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004262:DNA Restriction Enzymes; D006681:HLA-D Antigens / Q000235:genetics*; D006683:HLA-DQ Antigens / Q000235:genetics*; D006684:HLA-DR Antigens / Q000235:genetics*; D006239:Haplotypes; D006801:Humans
chemical_list: D006681:HLA-D Antigens; D006683:HLA-DQ Antigens; D006684:HLA-DR Antigens; D004247:DNA; D004262:DNA Restriction Enzymes