Ubiquitin system is composed of ubiquitin, ubiquitin_activating enzymes, Ubiquitin_conjugating enzymes, ubiquitin_protein ligases, ubiquitin_C_terminal hydrolase and 26S proteasomes.

• 泛肽系统由Ub、Ub活化酶、Ub结合酶、Ub_蛋白质连接酶、Ub_C末端水解酶和26S蛋白酶体组成。