The immunoglobulin fold family: sequence analysis and 3D structure comparisons
The immunoglobulin fold family: sequence analysis and 3D structure comparisons
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DOI：
10.1093/protein/12.7.563
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发表时间：
1999-07-01
期刊：
影响因子：
--
通讯作者：
Mornon, JP
中科院分区：
文献类型：
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作者：
Halaby, DM;Poupon, A;Mornon, JP
比较了52个涵盖免疫球蛋白折叠家族（IgFF）的Ig样结构域的三维结构，并根据其二级结构的保守性进行了分类。IgFF的成员是具有相似折叠（IG折叠）的远缘相关蛋白质或进化上不相关的蛋白质。本文描述了保守的共同核心的多重结构比对，并讨论了相应序列之间的相关性。虽然IgFF的成员在组织和物种分布或功能意义方面表现出广泛的异质性，但这些结构域的3D结构远比其序列保守。我们定义拓扑等价残基的Ig样结构域，描述了疏水性的共同核心，并讨论了额外的链的存在。二硫桥对IG折叠的稳定性不是必需的，但可能对结构域的紧密性有影响。基于序列和结构分析，我们建议引入两个新的亚型（C3和C4）到以前的分类，除了一个新的全球结构分类。IgFF亚群之间非常低的平均序列同一性表明存在分歧和趋同的进化过程，解释了超家族的广泛多样性。最后，本文综述表明，构成共同疏水核心的疏水残基对于解释高度分歧的序列如何具有相似的折叠是重要的。
Fifty-two 3D structures of Ig-like domains covering the immunoglobulin fold family (IgFF) were compared and classified according to the conservation of their secondary structures. Members of the IgFF are distantly related proteins or evolutionarily unrelated proteins with a similar fold, the Ig fold. In this paper, a multiple structural alignment of the conserved common core is described and the correlation between corresponding sequences is discussed. While the members of the IgFF exhibit wide heterogeneity in terms of tissue and species distribution or functional implications, the 3D structures of these domains are far more conserved than their sequences. We define topologically equivalent residues in the Ig-like domains, describe the hydrophobic common cores and discuss the presence of additional strands. The disulfide bridges, not necessary for the stability of the Ig fold, may have an effect on the compactness of the domains. Based upon sequence and structure analysis, we propose the introduction of two new subtypes (C3 and C4) to the previous classifications, in addition to a new global structural classification. The very low mean sequence identity between subgroups of the IgFF suggests the occurrence of both divergent and convergent evolutionary processes, explaining the wide diversity of the superfamily, Finally, this review suggest that hydrophobic residues constituting the common hydrophobic cores are important dues to explain how highly divergent sequences can adopt a similar fold.