Which came first, the lectin/classical pathway or the alternative pathway of complement?
Which came first, the lectin/classical pathway or the alternative pathway of complement?
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DOI：
10.1078/0171-2985-00137
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发表时间：
2002-09-01
期刊：
影响因子：
2.8
通讯作者：
Dodds, AW
中科院分区：
文献类型：
--
作者：
Dodds, AW
这是一个被广泛接受的免疫学准则，即替代途径更原始，因此在进化方面比凝集素/经典途径更古老。在无脊椎动物物种中发现的“C3”和“因子B”蛋白进一步加强了这一观点。然而，很明显，在脊椎动物谱系中发生了产生C3/C4/C5和因子B/C2的基因重复。因此，无脊椎动物蛋白质的命名可能是基于先入为主的观念，而不是坚实的结构或功能证据。凝集素和相关的MASP/C1 r/C1 s样蛋白已在无脊椎动物中发现，而替代途径的定义成分D因子迄今仅在硬骨鱼和高等物种中发现。达尔文进化论的一个原则是，复杂的系统是通过连续的小步骤发展起来的。我们可以想象，凝集素途径的进化有一系列步骤，包括识别非我。很难想象缺乏识别分子的替代途径如何在没有控制蛋白质保护自身免受攻击的情况下进化。
It is a widely accepted canon of immunology that the alternative pathway is more primitive and hence older in evolutionary terms than the lectin/classical pathway. This idea has been reinforced by the discovery of "C3" and "factor B" proteins in invertebrate species. However, it is clear that the gene duplications which gave rise to C3/C4/C5 and factor B/C2 occurred in the vertebrate lineage. Hence, the naming of the invertebrate proteins may be based on preconceptions rather than on solid structural or functional evidence. Lectins and associated MASP/C1r/C1s-like proteins have been found in invertebrates, while factor D, the defining component of an alternative pathway, has so far been found only in the bony fish and higher species. It is a principle of Darwinian evolution that complex systems develop through small sequential steps. It is possible to imagine such a series of steps for the evolution of a lectin pathway, involving as it does recognition of non-self. It is difficult to see how the alternative pathway, which lacks a recognition molecule, could have evolved without the prior development of control proteins to protect self from attack.