Gyllensten U, Bergström T, Josefsson A, Sundvall M, Erlich H A
Department of Medical Genetics, University of Uppsala, Sweden.
Tissue Antigens. 1996 Mar;47(3):212-21. doi: 10.1111/j.1399-0039.1996.tb02543.x.
The evolution of polymorphism at the Mhc class II DPB1 locus was studied by comparison of chimpanzee (Pan troglodytes), pygmy chimpanzee (Pan paniscus), gorilla (Gorilla gorilla) and human DPB1 alleles. Extensive polymorphism was found in all hominoids. The clustering of sequences in the phylogenetic tree is consistent with rapid generation of the DPB1 polymorphism. Analysis of the substitution pattern for human alleles shows an excess of non-synonymous changes to synonymous changes at antigen recognition sites, indicating that the amino acid polymorphism at these sites is being maintained by selection. By contrast, no excess of nonsynonymous changes was found at the antigen recognition sites of nonhuman hominoid species. Thus, it appears that diversifying selection on the DPB1 polymorphism has intensified in the lineage leading to humans. No evidence was found for the existence of ancient allelic lineages predating the divergence of the hominoid species. The number of synonymous differences among DPB1 alleles is lower than among DQB1 and DRB1 alleles, indicative of a more recent origin for the DPB1 polymorphism and consistent with the more rapid evolution suggested by the phylogenetic tree.
通过比较黑猩猩（Pan troglodytes）、倭黑猩猩（Pan paniscus）、大猩猩（Gorilla gorilla）和人类的DPB1等位基因，研究了Mhc II类DPB1基因座的多态性进化。在所有类人猿中都发现了广泛的多态性。系统发育树中序列的聚类与DPB1多态性的快速产生一致。对人类等位基因替代模式的分析表明，在抗原识别位点，非同义变化与同义变化相比过多，这表明这些位点的氨基酸多态性是由选择维持的。相比之下，在非人类类人猿物种的抗原识别位点未发现过多的非同义变化。因此，似乎在导致人类的谱系中，对DPB1多态性的多样化选择已经加强。没有发现早于类人猿物种分化的古老等位基因谱系存在的证据。DPB1等位基因之间的同义差异数量低于DQB1和DRB1等位基因之间的同义差异数量，这表明DPB1多态性的起源更近，并且与系统发育树所表明的更快进化一致。
