Most HLA haplotypes carry two expressed DR β-chain genes; in the DR4 haplotype, the polymorphic locus has been called DR β1 and the apparently nonpolymorphic locus has been called DR β2. We have isolated nearly full-length DR β-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 β 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 β1 or β2 locus. Comparison of our DR4 β1 sequence with DR β1 sequences isolated from other DR4-positive cells suggests that the alleles of DR4 β1 may have recently diverged from a common ancestor. The apparent lack of polymorphism of DR β2 may in part be a reflection of this recent divergence.
|Original language||English (US)|
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - 1987|