C1Q COMPONENT OF COMPLEMENT BINDS TO FIBRINOGEN AND FIBRIN
C1Q COMPONENT OF COMPLEMENT BINDS TO FIBRINOGEN AND FIBRIN
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DOI：
10.1021/bi00401a073
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发表时间：
1988-01-12
期刊：
影响因子：
2.9
通讯作者：
FURCHT, LT
中科院分区：
文献类型：
--
作者：
ENTWISTLE, RA;FURCHT, LT
采用固相直接结合法研究了补体成分C1 q与纤维蛋白原和纤维蛋白的相互作用。放射性标记的纤维蛋白原与C1 q结合的Scatchard分析表明，至少有两个高亲和力结合常数（Kd）计算为8.5和120 nM。与此相反，放射性去离子纤维蛋白与C1 q的结合仅显示出一类结合位点，计算的Kd为600 nM。纤维蛋白原-C1 q结合被证明减少作为增加的盐浓度的函数，表明在结合位点中存在带电氨基酸或离子强度诱导的结合的构象依赖性。在使用C1 q的分离片段的直接结合研究中，C1 q的胶原样结构域和C1 q的球状结构域都显示出结合纤维蛋白原，表明纤维蛋白原的至少一个结合位点位于C1 q的每个主要结构域中。添加凝血酶产生的纤维蛋白原肽，纤维蛋白肽A和B，增强C1 q-纤维蛋白原结合，再次表明复杂的结合相互作用。这些结果表明，C1 q和纤维蛋白原能够高亲和力的相互作用，可能有助于隔离这些复合物在肿瘤，免疫复合物沉积，或伤口的区域。
The interaction of complement component C1 q with fibrinogen and fibrin was studied by using a solid-phase direct binding assay. Scatchard analysis of radiodinated fibrinogen binding to C1q indicated at least two high-affinity binding constants (Kd) calculated as 8.5 and 120 nM. In contrast, binding of radiodionated fibrin to C1q showed only a single class of binding sites with a calculated Kd of 600 nM. Fibrinogen-C1q binding was shown to decrease as a function of increasing salt concentrations, indicating either the presence of charged amino acids in the binding sites or an ionic strength induced conformational dependency of the binding. In direct binding studies using isolated fragments of C1q, both the collagen-like domain of C1q and the globular domains of C1q were shown to bind fibrinogen, indicating at least one binding site for fibrinogen is located in each of the major domains of C1q. Addition of the thrombin-generated peptides of fibrinogen, fibrinopeptides A and B, enhanced C1q-fibrinogen binding, again indicating a complex binding interaction. These results indicate that C1q and fibrinogen are capable of high-affinity interactions that may serve to sequester these complexes in areas of tumors, immune complex deposition, or wounds.