Mitomo K, Fujita T, Iida K
J Exp Med. 1987 May 1;165(5):1424-9. doi: 10.1084/jem.165.5.1424.
This is the first report demonstrating that C3d receptor (CR2) has functional activity in regulating complement cascade. Purified CR2 was examined for its cofactor activity in factor I-mediated cleavage of membrane-bound iC3b. CR2 plus C3b inactivator (I) released C3c from EA 125I-iC3b, and the release was inhibited when CR2 was preincubated with OKB7 monoclonal anti-CR2. Furthermore, immunoelectroblotting analysis showed crossreactivity of CR2 with 57H anti-CR1. These results indicate that CR2 has functional and antigenic similarity to CR1, thus providing a supporting evidence for placement of CR2 as a member of the recently defined gene family of C3- and C4-regulatory proteins composed of CR1, C4-binding protein, and factor H.
这是首份证明C3d受体（CR2）在调节补体级联反应中具有功能活性的报告。检测了纯化的CR2在I因子介导的膜结合iC3b裂解中的辅因子活性。CR2加C3b灭活剂（I）可从EA 125I-iC3b中释放出C3c，当CR2与OKB7单克隆抗CR2预孵育时，这种释放受到抑制。此外，免疫印迹分析显示CR2与57H抗CR1有交叉反应性。这些结果表明CR2与CR1在功能和抗原性上相似，从而为将CR2归为最近定义的由CR1、C4结合蛋白和H因子组成的C3和C4调节蛋白基因家族成员提供了支持证据。
