中文摘要：

转运必需内体分选复合物（endosomal sorting complex required for transport，ESCRT）系统是真核细胞中完成内体（endosome）膜内陷以形成多囊泡体（multi-vesicular body，MVB）的分子机器，其主要功能是促进被泛素（ubiquitin）标记的膜蛋白的降解，还与细胞分裂、病毒出芽、细胞自噬以及真菌pH感知相关．ESCRT系统包括ESCRT-0，-I，-Ⅱ，一Ⅲ和Vps4-Vtal共5个蛋白．蛋白复合物．晶体学研究已经解析了大部分复合物的结构．其促使膜内陷的分子机理一般认为分3步．首先是ESCRT-I和-Ⅱ在内体膜上结合并促使内体膜内陷形成初始芽体．之后，ESCRT-Ⅲ在芽体颈部聚合并导致芽体的剪切，从而将内腔囊泡（intralumenal vesicles，ILVs）释放到内体腔内，形成MVB．最后，Vps4／Vtal复合物则以水解ATP提供能量将聚合的ESCRT-Ⅲ解聚以循环使用，完成更多的出芽过程．本文将对ESCRT系统的结构、出芽机理和生物功能几方面做一个综述．

英文摘要：

The endosomal sorting complex required for transport （ESCRT） system is essential for the degradation of ubiquitinated membrane proteins and comprises a major pathway for MVB （multi-vesicular body） formation. ESCRT is also involved in retrovirus budding, cell division, autophagy and fungi pH sensing. Five protein complexes were identified in the ESCR system： ESCRT-0, - I , -Ⅱ , -Ⅲ and Vps4-Vtal. ESCRT-I and -Ⅱ induce the formation of the initial bud during the budding process. ESCRT-Ⅲ forms a lattice at the endosomal membrane and completes the scission at the bud neck, and Vps4-Vtal complex finally disassembles the ESCRT-Ⅲ lattice to recycle ESCRT machinery components. This review summarizes the structural features, budding mechanism and biological roles of the ESCRT system.