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真核细胞主要含有两条蛋白质降解途径,即溶酶体途径和非溶酶体途径。前者主要降解通过摄粒作用或胞饮作用吞噬进入细胞的胞外蛋白质,后者则在称为蛋白酶复合体(20s/26s proteasome)的颗粒内进行,被降解的蛋白底物经过E_1(泛素激活酶)、E_2(泛素结合酶)和E_3(泛素连接酶)的作用与多聚泛素(ubiquitin)结合,从而提呈给26s蛋白酶复合体降解。26s蛋白酶复合体的催化中心为一20s多功能蛋白酶,它由4个环状结构组成,2个外圈各由7个α亚基组成,2个内圈则各有7个
Eukaryotic cells mainly contain two protein degradation pathways, the lysosomal pathway and the non-lysosomal pathway. The former mainly degrades the extracellular proteins that enter into the cell through phagocytosis or pinocytosis. The latter is performed in a particle called a protease complex (20s/26s proteasome). The degraded protein substrate undergoes E_1 (ubiquitin). The role of activating enzymes), E_2 (ubiquitin-conjugating enzyme) and E_3 (ubiquitin ligase) binds to ubiquitin and thus presents degradation of the 26s protease complex. The catalytic center of the 26s protease complex is a 20s multifunctional protease, which consists of 4 ring structures, each of which consists of 7 α subunits, and each of which has 7 inner rings.