Lu B Z, Nei M
Yi Chuan Xue Bao. 1989;16(2):140-50.
In order to explain difference and similarity in producing antibody diversity between immunoglobulin (Ig) and T cell receptor (TCR), authors compared both codon substitution and concerted evolution rate between the variable segment of Ig heavy (Ig VH) and that of TCR (TCR V). The protein sequences of TCR V alpha (including 8 gene segments from mouse and 3 from human), TCR V beta (including 11 from mouse and one from human) and T cell V gamma (including 2 from mouse and 4 from human) were compiled, as well as the protein sequences of Ig VH (3 from human, 11 from mouse, 3 from caiman and one from shark) were collected. It is shown that: (1) the nucleotide substitution of TCR V segment is 2.4 times as large as that of Ig VH in coding region; (2) as for concerted evolution, gene duplicate rates in TCR V and Ig VH are 1.7 X 10(-8) and 1.6 X 10(-8)/gene/year, respectively. The number of TCR V(V alpha equals to 100 and V beta equals to 30) is less than the one of Ig VH (VH equals to 300), for TCR V is subject to negative selection of major histocompatibility complex according to the neutral theory. We discussed that is somatic mutation or DNA rearrangement the main force in producing antibody diversity and are there pseudogenes in TCR V or not.
为了解释免疫球蛋白（Ig）和T细胞受体（TCR）在产生抗体多样性方面的异同，作者比较了Ig重链可变区（Ig VH）和TCR可变区（TCR V）之间的密码子替换率和协同进化率。汇编了TCR Vα（包括来自小鼠的8个基因片段和来自人类的3个基因片段）、TCR Vβ（包括来自小鼠的11个基因片段和来自人类的1个基因片段）以及T细胞Vγ（包括来自小鼠的2个基因片段和来自人类的4个基因片段）的蛋白质序列，同时收集了Ig VH（来自人类的3个、来自小鼠的11个、来自凯门鳄的3个和来自鲨鱼的1个）的蛋白质序列。结果表明：（1）TCR V区在编码区的核苷酸替换是Ig VH的2.4倍；（2）关于协同进化，TCR V和Ig VH的基因重复率分别为1.7×10⁻⁸和1.6×10⁻⁸/基因/年。TCR V（Vα等于100且Vβ等于30）的数量少于Ig VH（VH等于300），根据中性理论，TCR V受到主要组织相容性复合体的负选择。我们讨论了产生抗体多样性的主要力量是体细胞突变还是DNA重排，以及TCR V中是否存在假基因。
