Mature T cells bearing αβ T cell receptors react with foreign antigens bound to alleles of major histocompatibility complex proteins (MHC) that they were exposed to during their development in the thymus, a phenomenon known as positive selection. The structural basis for positive selection has long been debated. Here, using mice expressing one of two different T cell receptor β chains and various MHC alleles, we show that positive selection-induced MHC bias of T cell receptors is affected both by the germline encoded elements of the T cell receptor α and β chain and, surprisingly, dramatically affected by the non germ line encoded portions of CDR3 of the T cell receptor α chain. Thus, in addition to determining specificity for antigen, the non germline encoded elements of T cell receptors may help the proteins cope with the extremely polymorphic nature of major histocompatibility complex products within the species.

中文翻译：

---

T细胞受体CDR3α的体细胞生成部分有助于T细胞受体的MHC等位基因特异性

带有 αβ T 细胞受体的成熟 T 细胞与外来抗原反应，这些抗原与主要组织相容性复合蛋白 (MHC) 的等位基因结合，它们在胸腺发育过程中接触到的，这种现象称为正选择。积极选择的结构基础长期以来一直存在争议。在这里，使用表达两种不同 T 细胞受体 β 链之一和各种 MHC 等位基因的小鼠，我们表明正选择诱导的 T 细胞受体 MHC 偏向性受 T 细胞受体 α 和 β 链的种系编码元件和令人惊讶的是，T细胞受体α链的CDR3的非种系编码部分显着影响。因此，除了确定抗原的特异性，