Johnson G, Wu T T
Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60208, USA.
J Mol Evol. 1997 Mar;44(3):253-7. doi: 10.1007/pl00006142.
When human T cell receptor for antigen (TCR) alpha chain V-genes were compared pair-wise, the numbers of nucleotide differences showed a characteristic distribution; most were in the range of 100 to 200 differences out of a total of about 300 bases. The same distribution was observed for mouse TCR alpha chains. Even more interesting was that comparing human alpha chains and mouse alpha chains gave essentially the same nucleotide difference pattern. It is inferred from the large number of differences and from the nonspecificity of trans-species (human and mouse) nucleotide sequence differences of TCR V-genes that TCR alpha chains probably diverged early during evolution. The same feature was also observed for human and mouse TCR beta chains, although the alpha and beta chain V-genes were distinct. This evolutionary preservation could be of vital importance to the fidelity of the complicated trimolecular interactions among TCR alpha and beta chains, the processed peptide, and the major histocompatibility complex (MHC) class I or II molecules.
当对人类抗原T细胞受体（TCR）α链V基因进行两两比较时，核苷酸差异数量呈现出一种特征性分布；在总共约300个碱基中，大多数差异数量在100到200之间。小鼠TCRα链也观察到了相同的分布。更有趣的是，比较人类α链和小鼠α链时，得到了基本相同的核苷酸差异模式。从TCR V基因跨物种（人类和小鼠）核苷酸序列差异的大量存在以及非特异性可以推断，TCRα链可能在进化早期就发生了分化。人类和小鼠TCRβ链也观察到了相同的特征，尽管α链和β链的V基因是不同的。这种进化上的保守性对于TCRα链和β链、加工后的肽以及主要组织相容性复合体（MHC）I类或II类分子之间复杂的三分子相互作用的保真度可能至关重要。
