OCCURRENCE OF A POLYUBIQUITIN STRUCTURE IN UBIQUITIN-PROTEIN CONJUGATES
OCCURRENCE OF A POLYUBIQUITIN STRUCTURE IN UBIQUITIN-PROTEIN CONJUGATES
复制标题
DOI：
10.1016/0006-291x(85)91050-2
复制
发表时间：
1985-01-01
影响因子：
3.1
通讯作者：
HELLER, H
中科院分区：
文献类型：
--
作者：
HERSHKO, A;HELLER, H
在泛素介导的细胞内蛋白质降解途径中，几个[人红细胞]泛素分子通过酰胺键连接到蛋白质底物上。从蛋白质中氨基的数量来看，泛素-蛋白质结合物的数量和它们的表观分子尺寸比预期的要高。当通过还原甲基化封闭泛素的氨基时，它可以有效地与溶菌酶结合，但不能形成较高分子量的偶联物。相对分子质量较高的与天然泛素的结合物包含一个泛素分子与另一个泛素分子的氨基相连的结构。甲基化泛素刺激蛋白质在.apprx处分解。1/2天然泛素和125I-溶菌酶与甲基化泛素的分离结合物被网织红细胞提取物分解。多泛素链的形成显然不是蛋白质分解的必要条件，尽管它可能会加快这一过程的速度。
In the ubiquitin-mediated pathway for the degradation of intracellular proteins, several molecules of [human erythrocyte] ubiquitin are linked to the protein substrate by amide linkages. The number of ubiquitin-protein conjugates and their apparent molecular size are higher than expected from the number of amino groups in the protein. When the amino groups of ubiquitin were blocked by reductive methylation, it was efficiently conjugated to lysozyme, but the higher MW conjugates were not formed. The higher MW conjugates with native ubiquitin contain structures in which 1 molecule of ubiquitin is linked to an amino group of another molecule of ubiquitin. Methylated ubiquitin stimulated protein breakdown at .apprx. 1/2 the rate obtained with native ubiquitin, and isolated conjugates of 125I-lysozyme with methylated ubiquitin were broken down by reticulocyte extracts. The formation of polyubiquitin chains apparently is not obligatory for protein breakdown, though it may accelerate the rate of this process.