Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
Traffic. 2009 Sep;10(9):1362-75. doi: 10.1111/j.1600-0854.2009.00952.x. Epub 2009 Jun 9.
The ArfGAP Glo3 is required for coat protein I vesicle generation in the Golgi-endoplasmic reticulum (ER) shuttle. The best-understood role of Glo3 is the stimulation of the GTPase activity of Arf1. In this study, we characterized functional domains of the ArfGAP Glo3 and identified an interaction interface for coatomer, SNAREs and cargo in the central region of Glo3 (BoCCS region). The GAP domain together with the BoCCS region is necessary and sufficient for all vital Glo3 functions. Expression of a truncated Glo3 lacking the GAP domain results in a dominant negative growth phenotype in glo3Delta cells at 37 degrees C. This phenotype was alleviated by mutating either the BoCCS region or the Glo3 regulatory motif (GRM), or by overexpression of ER-Golgi SNAREs or the ArfGAP Gcs1. The GRM is not essential for Glo3 function; it may act as an intrinsic sensor coupling GAP activity to SNARE binding to avoid dead-end complex formation at the Golgi membrane. Our data suggest that membrane-interaction modules and cargo-sensing regions have evolved independently in ArfGAP1s versus ArfGAP2/3s.
ArfGAP Glo3 对于高尔基体-内质网（ER）穿梭中的衣壳蛋白 I 囊泡的生成是必需的。Glo3 最被理解的作用是刺激 Arf1 的 GTP 酶活性。在这项研究中，我们对 ArfGAP Glo3 的功能结构域进行了表征，并在 Glo3 的中心区域（BoCCS 区域）鉴定了一个与衣壳蛋白、SNARE 和货物相互作用的界面。GAP 结构域连同 BoCCS 区域对于 Glo3 的所有重要功能都是必需和充分的。表达缺乏 GAP 结构域的截短 Glo3 会导致 glo3Delta 细胞在 37°C 时表现出显性负增长表型。这种表型可以通过突变 BoCCS 区域或 Glo3 调节基序（GRM）、过表达 ER-Golgi SNARE 或 ArfGAP Gcs1 来缓解。GRM 对于 Glo3 功能不是必需的；它可能作为一个内在的传感器，将 GAP 活性与 SNARE 结合耦联起来，以避免在高尔基体膜上形成无效的复合物。我们的数据表明，膜相互作用模块和货物感应区域在 ArfGAP1s 与 ArfGAP2/3s 中是独立进化的。
