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人 C3b/C4b 受体(CR_1)为一分子量为200 000的单链红细胞膜糖蛋白,可表达于 T、B 淋巴细胞、单核细胞、肥大细胞、多形核白细胞、红细胞、肾小球足突细胞上。CR_1既为带 C3b 和 C4b 的配体的受体,又为补体活化过程中的调节蛋白。CR_1的功能包括介导对红细胞及细菌的吞噬对小型免疫复合物的内吞,并产生第二信号。红细胞CR_1结合带有 C3b 或 C4b 的免疫复合物,将它们运至肝和脾脏的单核吞噬细胞系统 CR_1还为Ⅰ因子介导的 C3b,C4b 裂解的辅因子,加速补体第一及第二途径 C3转化酶的衰变。
Human C3b / C4b receptor (CR_1) is a single-chain erythrocyte membrane glycoprotein with a molecular weight of 200 000. It can be expressed in T, B lymphocytes, monocytes, mast cells, polymorphonuclear leukocytes, erythrocytes, glomerular foot On the cells. CR_1 is both a receptor for ligands with C3b and C4b and a regulatory protein for complement activation. The function of CR_1 includes mediating the endocytosis of small immune complexes by phagocytosis of erythrocytes and bacteria, and generating a second signal. CR_1 binds to immune complexes with C3b or C4b and translocates them to the liver and spleen of the mononuclear phagocyte system. CR_1 is also a factor I-mediated cofactor for C3b and C4b cleavage, accelerating the first and second complement pathways C3 convertase decay.