Champagne E, Sagman U, Biondi A, Lewis W H, Mak T W, Minden M D
Ontario Cancer Institute Bioresearch Department, Toronto, Canada.
Eur J Immunol. 1988 Jul;18(7):1033-8. doi: 10.1002/eji.1830180710.
The vast majority of T cells express an antigen receptor (TcR) composed of an alpha/beta heterodimer. The alpha and beta chains are encoded for by a set of variable (V), joining (J) and constant (C) region genes. Unlike the J genes of the beta chain which are limited in number and are clustered close to the constant region, the J alpha genes are spread over an 85-kilobase DNA region, upstream of the C alpha gene. We have isolated the complete J alpha locus, bounded on the 5' side by the C sequence of the delta gene and on the 3' side by the C sequence of the alpha gene. The experiments described here demonstrate that the J gene segments extend 75 kb 5' of C alpha and participate equally in generating the diversity of the alpha chain in peripheral T cells. Similarly, in leukemic T cell lines, rearrangements occurred over the entire locus and involved both alleles. Densitometry data suggest that in most peripheral T cells both alleles also are rearranged; thus, allelic exclusion in the alpha locus does not occur at the level of rearrangement. In three cell lines, an identical rearrangement has occurred on one allele in a region located 10 kb from the 5' end of the locus.
绝大多数T细胞表达由α/β异二聚体组成的抗原受体（TcR）。α链和β链由一组可变（V）、连接（J）和恒定（C）区基因编码。与β链的J基因数量有限且聚集在恒定区附近不同，Jα基因分布在Cα基因上游85千碱基的DNA区域。我们分离出了完整的Jα基因座，其5'端由δ基因的C序列界定，3'端由α基因的C序列界定。此处描述的实验表明，J基因片段在Cα的5'端延伸75 kb，并同样参与在外周T细胞中产生α链的多样性。同样，在白血病T细胞系中，重排在整个基因座上发生，且涉及两个等位基因。密度测定数据表明，在大多数外周T细胞中，两个等位基因也发生了重排；因此，α基因座上的等位基因排斥并非发生在重排水平。在三个细胞系中，在距离基因座5'端10 kb的区域，一个等位基因上发生了相同的重排。
