Tseng J, Mortensen R F
Department of Microbiology, Ohio State University, Columbus 43210.
Mol Immunol. 1988 Aug;25(8):679-86. doi: 10.1016/0161-5890(88)90103-4.
Human C-reactive protein (CRP) is an acute phase reactant that is selectively deposited at sites of tissue damage. CRP binds with high affinity to purified plasma fibronectin (Fn) when the Fn is immobilized on a surface or matrix via either specific IgG antibody or by gelatin. The CRP to Fn binding is saturable at a molar ratio of CRP/Fn of approximately 9 with a Kd = 1.47 x 10(-7) M and requires Ca2+. The binding site on Fn for CRP was localized to the C-terminal portion by using monoclonal antibodies (mAbs) to Fn as competitive inhibitors of CRP. The binding involves the phosphorylcholine (PC)-binding site of CRP since the addition of PC inhibits binding to Fn and those mAbs to CRP that bind at or near the PC-binding site selectively inhibit the CRP to Fn binding. In addition the mouse IgA myeloma protein TEPC-15, which is specific for PC, also competes with CRP for binding sites on Fn. A mAb to the mouse PC-binding idiotype T-15, which also reacts with the PC-binding site of CRP, inhibits the binding of CRP to Fn. The findings suggest that CRP may play a role in the formation of the extracellular matrix needed for tissue repair. The CRP-Fn interaction may be one of the explanations for the observation of selective deposition of CRP at sites of tissue injury.
人C反应蛋白（CRP）是一种急性期反应物，可选择性沉积于组织损伤部位。当纤连蛋白（Fn）通过特异性IgG抗体或明胶固定在表面或基质上时，CRP能以高亲和力与之结合。CRP与Fn的结合在CRP/Fn摩尔比约为9时达到饱和，解离常数（Kd）=1.47×10⁻⁷ M，且需要Ca²⁺。通过使用针对Fn的单克隆抗体（mAb）作为CRP的竞争性抑制剂，将Fn上CRP的结合位点定位到C末端部分。这种结合涉及CRP的磷酸胆碱（PC）结合位点，因为添加PC会抑制与Fn的结合，并且那些在PC结合位点或其附近结合的CRP单克隆抗体选择性地抑制CRP与Fn的结合。此外，对PC具有特异性的小鼠IgA骨髓瘤蛋白TEPC - 15也与CRP竞争Fn上的结合位点。一种针对小鼠PC结合独特型T - 15的单克隆抗体，它也与CRP的PC结合位点反应，可抑制CRP与Fn的结合。这些发现表明，CRP可能在组织修复所需的细胞外基质形成中发挥作用。CRP - Fn相互作用可能是对CRP在组织损伤部位选择性沉积这一观察结果的一种解释。
