Lanoix J, Ouwendijk J, Stark A, Szafer E, Cassel D, Dejgaard K, Weiss M, Nilsson T
Cell Biology and Biophysics Programme, European Molecular Biology Laboratory, D-69017 Heidelberg, Germany.
J Cell Biol. 2001 Dec 24;155(7):1199-212. doi: 10.1083/jcb.200108017. Epub 2001 Dec 17.
We present evidence for two subpopulations of coatomer protein I vesicles, both containing high amounts of Golgi resident proteins but only minor amounts of anterograde cargo. Early Golgi proteins p24alpha2, beta1, delta1, and gamma3 are shown to be sorted together into vesicles that are distinct from those containing mannosidase II, a glycosidase of the medial Golgi stack, and GS28, a SNARE protein of the Golgi stack. Sorting into each vesicle population is Arf-1 and GTP hydrolysis dependent and is inhibited by aluminum and beryllium fluoride. Using synthetic peptides, we find that the cytoplasmic domain of p24beta1 can bind Arf GTPase-activating protein (GAP)1 and cause direct inhibition of ArfGAP1-mediated GTP hydrolysis on Arf-1 bound to liposomes and Golgi membranes. We propose a two-stage reaction to explain how GTP hydrolysis constitutes a prerequisite for sorting of resident proteins, yet becomes inhibited in their presence.
我们提供了证据，证明存在两种衣被蛋白I囊泡亚群，两者都含有大量高尔基体驻留蛋白，但只有少量顺行货物。早期高尔基体蛋白p24α2、β1、δ1和γ3被证明一起被分选到与含有甘露糖苷酶II（一种中间高尔基体堆栈的糖苷酶）和GS28（一种高尔基体堆栈的SNARE蛋白）的囊泡不同的囊泡中。进入每个囊泡群体的分选依赖于Arf-1和GTP水解，并受到铝和氟化铍的抑制。使用合成肽，我们发现p24β1的细胞质结构域可以结合Arf GTP酶激活蛋白（GAP）1，并直接抑制ArfGAP1介导的与脂质体和高尔基体膜结合的Arf-1上的GTP水解。我们提出了一个两阶段反应来解释GTP水解如何构成驻留蛋白分选的先决条件，但在它们存在的情况下会受到抑制。
