Ubiquitin-activating enzyme, E1, is associated with maturation of autophagic vacuoles.
Ubiquitin-activating enzyme, E1, is associated with maturation of autophagic vacuoles.
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泛素激活酶E1与自噬液泡的成熟有关。
DOI：
10.1083/jcb.118.2.301
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发表时间：
1992-07
影响因子：
7.8
通讯作者：
Schwartz, A L
中科院分区：
文献类型：
--
作者：
Lenk, S E;Dunn, W A Jr;Trausch, J S;Ciechanover, A;Schwartz, A L
泛素激活酶E1是启动泛素与靶蛋白共价连接的多步途径所必需的。一个CHO细胞系含有一个突变的不耐热的E1，TS20，已经被证明在有限的温度下在应激诱导的蛋白质降解方面存在缺陷(Gropper等，1991)。J.Biol.化学。266：3602-3610)。亲本E36细胞对限制性温度的反应是通过刺激溶酶体介导的蛋白质降解两倍进行的。在TS20细胞中没有观察到这样的反应。这些细胞在39.5摄氏度时没有加速降解，伴随着自溶酶体的积累。这些降解的自噬空泡的体积至少是E36细胞(30.5℃或39.5℃)或TS20细胞(30.5℃)的6倍。这些空泡是酸性的，含有酸性磷酸酶和组织蛋白L，但与E36细胞中观察到的自溶酶体不同，明显缺乏泛素结合蛋白。综上所述，我们的结果表明，在由于E1的热灭活而不能产生泛素-蛋白质结合物的TS20细胞中，自噬小体形成和成熟为自溶酶体是正常的，但自溶酶体到残余体的转换被扰乱。
The ubiquitin-activating enzyme, E1, is required for initiating a multi- step pathway for the covalent linkage of ubiquitin to target proteins. A CHO cell line containing a mutant thermolabile E1, ts20, has been shown to be defective in stress-induced degradation of proteins at restrictive temperature (Gropper et al., 1991. J. Biol. Chem. 266:3602- 3610). Parental E36 cells responded to restrictive temperature by stimulating lysosome-mediated protein degradation twofold. Such a response was not observed in ts20 cells. The absence of accelerated degradation in these cells at 39.5 degrees C was accompanied by an accumulation of autolysosomes. The fractional volume of these degradative autophagic vacuoles was at least sixfold greater than that observed for either E36 cells at 30.5 degrees or 39.5 degrees C, or ts20 cells at 30.5 degrees C. These vacuoles were acidic and contained both acid phosphatase and cathepsin L, but, unlike the autolysosomes observed in E36 cells, ubiquitin-conjugated proteins were conspicuously absent. Combined, our results suggest that in ts20 cells, which are unable to generate ubiquitin-protein conjugates due to heat inactivation of E1, the formation and maturation of autophagosomes into autolysosomes is normal, but the conversion of autolysosomes into residual bodies is disrupted.