Kehoe J M, Capra J D
Proc Natl Acad Sci U S A. 1972 Aug;69(8):2052-5. doi: 10.1073/pnas.69.8.2052.
Immunoglobulin heavy chains of myeloma proteins from dogs and cata have been subjected to automated sequence analysis. When the results were compared with human heavy-chain sequences, all the dog and cat proteins could be unequivocally assigned to the V(H)III subgroup. This pattern contrasts with that in human proteins in which only 25% of all heavy chains sequenced belong to this subgroup. The 30 residues at the NH(2) termini of dog, cat, and human heavy chains had sequence identities near or exceeding 90%, in contrast to established interspecies sequence homologies of constant regions of about 60%. Some genes of the immunoglobulin heavy-chain variable region thus appear to have been conserved through a considerable period of evolutionary time. The analyses also showed that the presence of certain amino acids at certain positions in these heavy chains could be correlated with the species of origin. The occurrence of such "phylogenetically associated" residues is most consistent with the presence of a restricted number of genes in the heavy-chain variable region pool.
犬类和猫类骨髓瘤蛋白的免疫球蛋白重链已进行自动序列分析。将结果与人重链序列比较时，所有犬类和猫类蛋白都能明确归属于V(H)III亚组。这种模式与人类蛋白不同，人类测序的所有重链中只有25%属于该亚组。犬类、猫类和人类重链NH(2)末端的30个残基序列同一性接近或超过90%，而恒定区已确定的种间序列同源性约为60%。因此，免疫球蛋白重链可变区的一些基因似乎在相当长的进化时间内得到了保守。分析还表明，这些重链中特定位置某些氨基酸的存在与起源物种相关。这种“系统发育相关”残基的出现与重链可变区基因库中数量有限的基因存在最为一致。
