中文摘要：

泛素（ubiquitin，Ub）-蛋白酶体降解系统是广泛存在于真核细胞中，特异识别进而靶向降解底物蛋白的一种途径，参与了细胞生长、增殖以及凋亡等重要过程，因此对维持和调节细胞的动态平衡起着非常重要的作用。泛素是一个小肽，泛素化修饰是指泛素在ATP存在的情况下，经一系列酶，即泛素活化酶（ubiquitin—activating enzyme，E1）、泛素结合酶（ubiquitin—conjugating enzyme，E2）以及泛素连接酶（ubiquitin—ligase enzyme，E3）的催化作用

英文摘要：

Ubiquitin ligases are an important component in ubiquitination system,which can recognize substrate proteins specially to promote their degradation.Closely related to the generation and development of many tumors,ubiquitin ligases can regulate the growth,differentiation and apoptosis of cells by influencing protein stability,which makes them a potential new target for tumor molecular therapy.There are many kinds of ubiquitin ligases,mainly including APC/C and SCF complex.This article will introduce the structures and functions of these two kinds of ubiquitin ligases and their roles in the tumor generation and development.