title: Evolutionary and genetic implications of sequence variation in two nonallelic HLA-DR beta-chain cDNA sequences.
abstract: Most HLA haplotypes carry two expressed DR beta-chain genes; in the DR4 haplotype, the polymorphic locus has been called DR beta 1 and the apparently nonpolymorphic locus has been called DR beta 2. We have isolated nearly full-length DR beta-chain cDNA clones representing each of these two loci from a cell line homozygous for DR4 and Dw4. The clones have been sequenced and the sequences compared with published DR beta cDNA sequences derived from other haplotypes. A comparison of our sequences with other published cDNA sequences did not allow assignment of these other sequences to either the beta 1 or beta 2 locus. Comparison of our DR4 beta 1 sequence with DR beta 1 sequences isolated from other DR4-positive cells suggests that the alleles of DR4 beta 1 may have recently diverged from a common ancestor. The apparent lack of polymorphism of DR beta 2 may in part be a reflection of this recent divergence.
authors.forename: J M
authors.initials: JM
authors.lastname: Curtsinger
authors.forename: J M
authors.initials: JM
authors.lastname: Hilden
authors.forename: J S
authors.initials: JS
authors.lastname: Cairns
authors.forename: F H
authors.initials: FH
authors.lastname: Bach
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D002460:Cell Line; D004247:DNA / Q000032:analysis*; D014644:Genetic Variation; D006681:HLA-D Antigens / Q000235:genetics*; D006684:HLA-DR Antigens / Q000235:genetics*; D006239:Haplotypes; D006720:Homozygote; D006801:Humans; D046911:Macromolecular Substances; D011110:Polymorphism, Genetic; D012689:Sequence Homology, Nucleic Acid
chemical_list: D006681:HLA-D Antigens; D006684:HLA-DR Antigens; D046911:Macromolecular Substances; D004247:DNA