The crystal structure of the globular head of complement protein C1q provides a basis for its versatile recognition properties
The crystal structure of the globular head of complement protein C1q provides a basis for its versatile recognition properties
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DOI：
10.1074/jbc.m307764200
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发表时间：
2003-11-21
影响因子：
4.8
通讯作者：
Arlaud, GJ
中科院分区：
文献类型：
--
作者：
Gaboriaud, C;Juanhuix, J;Arlaud, GJ
C1 q是一种多功能识别蛋白，可与多种免疫和非免疫配体结合，并触发补体经典途径的激活。负责其识别特性的C1 q球状结构域的晶体结构现在已经被解决并细化到1.9埃的分辨率。该结构揭示了一个紧凑的，几乎是球形的异源三聚体组装在一起，主要通过非极性相互作用，与钙离子结合在顶部。C1 q球状结构域的异源三聚体组装似乎是这种蛋白质的多功能识别特性的关键因素。提出了C1 q球状结构域与其两种生理配体C-反应蛋白和IgG复合的合理三维模型，突出了C1 q的两种可能的识别模式。C1 q/人IgG 1模型表明IgG的铰链区及其Fab结构域在C1 q结合中的相对取向具有关键作用。
C1q is a versatile recognition protein that binds to an amazing variety of immune and non-immune ligands and triggers activation of the classical pathway of complement. The crystal structure of the C1q globular domain responsible for its recognition properties has now been solved and refined to 1.9 Angstrom of resolution. The structure reveals a compact, almost spherical heterotrimeric assembly held together mainly by non-polar interactions, with a Ca2+ ion bound at the top. The heterotrimeric assembly of the C1q globular domain appears to be a key factor of the versatile recognition properties of this protein. Plausible three-dimensional models of the C1q globular domain in complex with two of its physiological ligands, C-reactive protein and IgG, are proposed, highlighting two of the possible recognition modes of C1q. The C1q/human IgG1 model suggests a critical role for the hinge region of IgG and for the relative orientation of its Fab domain in C1q binding.