Rask L, Lindblom J B, Peterson P A
Eur J Immunol. 1976 Feb;6(2):93-100. doi: 10.1002/eji.1830060205.
HLA antigens are coded for by three closely linked loci. The gene products of the first and second locus are known to be very similar in overall structure. Antigens coded for by the third locus were examined with regard to their chemical and immunological relationship to the first and second loci gene products. It is demonstrated that the third locus antigens are composed of two types of polypeptide chains, the smaller of which is identical to beta2-microglobulin. The alloantigenic polypeptide chain has an apparent molecular weight of 48 000 when solubilized by detergen treatment and about 35 000 when released from the cell membrane by proteolysis. These data together with size and shape analyses by gel chromatography and sedimentation velocity determinations show that HLA antigens from the three subloci are indistinguishable with the techniques employed. Suggestive evidence was obtained that the third locus antigens are more sensitive to proteolysis than the first and second locus antigens. The similarity between the three gene products was also evident on cyanogen bromide fragmentation of the polypeptide chains. Furthermore, rabbit antibodies against antigens coded for by the first locus cross-reacted extensively with antigens from the second and third locus. This study therefore lends strong credence to the view that the three HLA antigen subloci have arisen by gene duplications of a common ancestral gene.
人类白细胞抗原（HLA）抗原由三个紧密连锁的基因座编码。已知第一和第二个基因座的基因产物在整体结构上非常相似。对第三个基因座编码的抗原与其第一和第二个基因座基因产物的化学及免疫关系进行了研究。结果表明，第三个基因座抗原由两种类型的多肽链组成，其中较小的多肽链与β2-微球蛋白相同。经去污剂处理溶解后，同种异体抗原多肽链的表观分子量为48000，经蛋白水解从细胞膜释放后约为35000。这些数据以及凝胶色谱法进行的大小和形状分析以及沉降速度测定表明，采用这些技术无法区分来自三个亚基因座的HLA抗原。有迹象表明，第三个基因座抗原比第一和第二个基因座抗原对蛋白水解更敏感。多肽链经溴化氰裂解后，三种基因产物之间的相似性也很明显。此外，针对第一个基因座编码抗原的兔抗体与来自第二个和第三个基因座的抗原发生广泛交叉反应。因此，这项研究有力地支持了以下观点：三个HLA抗原亚基因座是由一个共同祖先基因的基因复制产生的。
