Mondragón-Palomino M, Piñero D, Nicholson-Weller A, Laclette J P
Department of Immunology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, A.P. 70228, 04510 México, D.F., México.
J Mol Evol. 1999 Aug;49(2):282-9. doi: 10.1007/pl00006550.
The plasma complement system comprises several activation pathways that share a common terminal route involving the assembly of the terminal complement complex (TCC), formed by C5b-C9. The order of emergence of the homologous components of TCC (C6, C7, C8alpha, C8beta, and C9) has been determined by phylogenetic analyses of their amino acid sequences. Using all the sequence data available for C6-C9 proteins, as well as for perforins, the results suggested that these TCC components originated from a single ancestral gene and that C6 and C7 were the earliest to emerge. Our evidence supports the notion that the ancestral gene had a complex modular composition. A series of gene duplications in combination with a tendency to lose modules resulted in successive complement proteins with decreasing modular complexity. C9 and perforin apparently are the result of different selective conditions to acquire pore-forming function. Thus C9 and perforin are examples of evolutionary parallelism.
血浆补体系统由几种激活途径组成，这些途径共享一条共同的末端途径，该途径涉及由C5b - C9形成的末端补体复合物（TCC）的组装。通过对TCC同源成分（C6、C7、C8α、C8β和C9）的氨基酸序列进行系统发育分析，确定了它们出现的顺序。利用所有可获得的C6 - C9蛋白以及穿孔素的序列数据，结果表明这些TCC成分起源于一个单一的祖先基因，并且C6和C7是最早出现的。我们的证据支持这样一种观点，即祖先基因具有复杂的模块化组成。一系列基因复制与模块丢失的趋势相结合，导致了模块化复杂性逐渐降低的连续补体蛋白。C9和穿孔素显然是获得成孔功能的不同选择条件的结果。因此，C9和穿孔素是进化平行性的例子。
