Arf GAP2 is positively regulated by coatomer and cargo
Arf GAP2 is positively regulated by coatomer and cargo
复制标题
DOI：
10.1016/j.cellsig.2009.03.006
复制
发表时间：
2009-07-01
影响因子：
4.8
通讯作者：
Randazzo, Paul A.
中科院分区：
文献类型：
--
作者：
Luo, Ruibai;Ha, Vi Luan;Randazzo, Paul A.
Arf GAP2 是在高尔基体中发挥作用的四个 Arf GAP 之一。我们表征了 Arf GAP2 的动力学及其调控。与纯化的 Arf GAP1 相比，纯化的 Arf GAP2 几乎没有活性。在我们检查的潜在调节剂中，涂层异构体的效果最大，刺激活性一到两个数量级。该效应是双相的，在 50 nM 涂层异构体处观察到半最大激活，在大约 150 nM 涂层异构体处观察到激活峰值。 Arf GAP2 的涂层异构体激活作用比报道的 Arf GAP1 更强。与涂层异构体相比，磷酸肌醇和囊泡曲率变化对 GAP 活性的影响较小；然而，两者都增加了涂层异构体依赖性活性。来自 p24 货物蛋白的肽使 Arf GAP2 活性额外增加 2 至 4 倍。货物肽的作用取决于涂层异构体。过表达货物蛋白 p25 会降低细胞 Arfl.GTP 水平。 Arf GAP1 和 Arf GAP2 对涂层异构体的不同敏感性可以协调它们的活性。基于 Arf GAP1 和 2 的共同调控特征，我们提出了一种货物选择机制，其中货物与外壳蛋白结合触发的 GTP 水解与外壳聚合偶联。由爱思唯尔公司出版
Arf GAP2 is one of four Arf GAPs that function in the Golgi apparatus. We characterized the kinetics of Arf GAP2 and its regulation. Purified Arf GAP2 had little activity compared to purified Arf GAP1. Of the potential regulators we examined, coatomer had the greatest effect, stimulating activity one to two orders of magnitude. The effect was biphasic, with half-maximal activation observed at 50 nM coatomer and activation peaking at approximate to 150 nM coatomer. Activation by coatomer was greater for Arf GAP2 than has been reported for Arf GAP1. The effects of phosphoinositides and changes in vesicle curvature on GAP activity were small compared to coatomer; however, both increased coatomer-dependent activity. Peptides from p24 cargo proteins increased Arf GAP2 activity by an additional 2- to 4-fold. The effect of cargo peptide was dependent on coatomer. Overexpressing the cargo protein p25 decreased cellular Arfl.GTP levels. The differential sensitivity of Arf GAP1 and Arf GAP2 to coatomer could coordinate their activities. Based on the common regulatory features of Arf GAP1 and 2, we propose a mechanism for cargo selection in which GTP hydrolysis triggered by cargo binding to the coat protein is coupled to coat polymerization. Published by Elsevier Inc.