补体膜辅蛋白的研究进展

Advances in membrane cofactor protein

补体膜辅蛋白是分子质量为 4 5 0 0 0～ 70 0 0 0u的单链穿膜糖蛋白 ,为补体活化调节基因家族的成员之一。补体膜辅蛋白的细胞分布广泛 ,但不同类型的细胞表达的数量有所不同。现已用探针从cDNA文库中获得其cDNA克隆片断并测序 ,基因组结构已确定。补体膜辅蛋白的主要功能是辅助Ⅰ因子降解C3b和C4b ,它和其它补体成员一起有效控制补体活化 ,保护宿主细胞免受补体介导的杀伤。此外 ,补体膜辅蛋白还可作为麻疹病毒受体 ,在生殖免疫。

Membrane cofactor protein is a 45000～70000 u single strand transmembrane glycoprotein, which belongs to the RCA family. Membrane lofactor protein is widely expressed on the surface of cells, but with tissue specific. It serves as a cofactor of serine protease factor Ⅰ for inactivation of complement C3b and C4b. Its primary role is to protect host cells from homologous complement attack by inactivating C3b/C4b deposited on membrane. It also acts as receptor for measles virus some kinds of bacteria and for a putative ligand on oocytes, and application for xenotransplantation.