人类补体C8结构与功能研究进展

Review of Structure and Function of Human Complement Protein C8

人类补体C8是组成膜攻击复合物(MAC)的五种成分之一。C8α、C8β与C6、C7、C9具有较强的同源性,而C8γ则属于分泌性蛋白家族成员,具有与小的疏水性配体结合的能力。形成膜攻击复合物的其他补体成分与C8的结合位点大多位于α、β的MACPF结构域。目前,大多数关于补体成分的研究主要集中于补体C3,鉴于补体C8在形成MAC中的重要性,在此就C8的结构与功能予以综述。

Human C8 is one of five components which interact to form the membrane attack complex（MAC）.C8αand C8βare homologous to C6,C7 and C9,both containing N-and C-terminal modules and an intervening 40-kDa segment referred to as the membrane attack complex/perforin（MACPF）domain.By comparison,C8γ is distinct in that it belongs to the lipocalin family of small,secreted proteins which have the common ability to bind small hydrophobic ligands.Recent studies show that the binding sites of the other components forming MAC and C8 mostly lie in the MACPF domain.This review summarizes the current status of C8 structure and function,and the progress made from efforts to determine its role in the complement system.