Human T-cell gamma genes contain N segments and have marked junctional variability.
Human T-cell gamma genes contain N segments and have marked junctional variability.
复制标题
人类 T 细胞伽玛基因包含 N 个片段，并具有显着的连接变异性。
作者：
Quertermous,T;Strauss,W;Murre,C;Dialynas,DP;Strominger,JL;Seidman,JG
γ 链基因由种系 DNA 中的免疫球蛋白样基因片段编码，这些基因片段在 T 细胞的体细胞发育过程中重新排列，形成活性基因 1-7。这些基因产生的蛋白质尚未被鉴定，并且这些基因可以表达的蛋白质的多样性尚未确定。我们期望表达的γ链的多样性是由产生其他免疫球蛋白样基因多样性的相同三种机制产生的：（1）种系可变区（V）和连接区（J）区库； (2)体细胞突变； (3) 连接多样性8,9。为了定义这些机制中的每一个对γ链多样性产生的贡献，已经表征了几个γ链互补克隆和重排的γ链基因。大多数这些克隆似乎编码有缺陷的γ链，可变区和恒定区部分连接在一起，这样它们就不会在同一阅读框中翻译。在此，我们报道人类 T 细胞 γ 链的种系 J 区多样性非常有限，体细胞突变对克隆片段编码的 γ 链的多样性没有贡献。然而，这些γ链基因的连接多样性非常广泛。我们建议N序列（模板独立序列）已被酶促插入到所有表征的γ链基因中。
Theγ-chain genes are encoded by immunoglobulin-like gene segments in germline DNA which rearrange during the somatic development of T cells to form an active gene1–7. The protein produced by these genes has not been identified and the diversity of the proteins that the genes can express has not been determined. We expect that the diversity of expressedγ-chains is produced by the same three mechanisms that produce diversity of other immunoglobulin-like genes: (1) germline variable (V) and joining (J) region repertoires; (2) somatic mutation; and (3) junctional diversity8,9. To define the contribution of each of these mechanisms to the generation ofγ-chain diversity, severalγ-chain complementary clones and rearrangedγ-chain genes have been characterized. Most of these clones seem to encode a defectiveγ-chain, the variable- and constant-region portions being joined such that they would not be translated in the same reading frame. Here we report that the germlineJ-region diversity of the human T-cellγ-chain is very limited and that somatic mutation does not contribute to the diversity of theγ-chains encoded by the cloned segments. However, the junctional diversity of theseγ-chain genes is extensive. We suggest thatNsequences (template-independent sequences) have been inserted enzymatically into all of theγ-chain genes characterized.