The formation of COPII-coated vesicles initiates with the activation of Sar1 by its guanine-nucleotide exchange factor (GEF), Sec12 (Barlowe and Schekman, 1993; Barlowe et al., 1993). The activated Sar1 recruits Sec23 and Sec24 heterodimers to form the pre-budding complex with cargo proteins (Matsuoka et al., 1998 ; Bi et al., 2002 ; Sato and ...

2023年2月3日 · Sar1 activation and COPII vesicle formation. Sar1 activation at ERES by its cognate GEF Sec12 results in membrane association (left, zoom on membrane). Multiple Sar1-binding events result in membrane deformation through sequential binding of Sec23-Sec24 inner and Sec13-Sec31 outer coat subunits.

2016年9月1日 · The Sar1 GTPase controls coat assembly on coat protein complex II (COPII)-coated vesicles, which mediate protein transport from the endoplasmic reticulum (ER) to the Golgi. The GTP-bound form of Sar1, activated by the ER-localized guanine nucleotide exchange factor (GEF) Sec12, associates with the ER membrane.

2020年4月17日 · Sar1 is activated on the surface of the ER by Sec12, a membrane-anchored GEF (guanine nucleotide exchange factor). Here we report the crystal structure of the complex between Sar1 and the cytoplasmic domain of Sec12, representing a …

2006年9月29日 · In this study, we report the three-dimensional structure of GDP bound Sar1 at low concentration of Mg ion. Two Sar1-GDP molecules form asymmetric dimer (Mol A and Mol B) in the crystallographic asymmetric unit. While Mol B has Mg ion present, Mol A does not, suggesting weaker binding of Mol A of Sar1-GDP to Mg ion.

A guanine nucleotide exchange factor (GEF) mediates the exchange of GDP for GTP in Sar/Arf. GTP-loaded Sar/Arf undergoes a conformational change of the two switch and interswitch regions, triggering the extrusion of the helix from the pocket.

当Sar1在鸟苷酸交换因子(GEF:guanine nucleotide exchange factor)Sec12参与下GDP与GTP进行了交换,与激活蛋白(GAP: GTPase-activating proteins）Sec23作用，诱导Sec23和Sec24蛋白的结合,接着是Sec13和Sec31蛋白的结合。

Here, we demonstrate that Sar1 acts as the curvature-sensing component of the COPII coat complex and highlight the ability of Sar1 to bind more avidly to membranes of high curvature. Additionally, using an atomic force microscopy-based approach, we further show that the intrinsic GTPase activity of Sar1 is necessary for remodeling lipid bilayers.

2016年9月1日 · The Sar1 GTPase controls coat assembly on coat protein complex II (COPII)-coated vesicles, which mediate protein transport from the endoplasmic reticulum (ER) to the Golgi. The GTP-bound form of Sar1, activated by the ER-localized guanine nucleotide exchange factor (GEF) Sec12, associates with the E …

2020年4月1日 · Sar1 is activated on the surface of the ER by Sec12, a membrane‐anchored GEF (guanine nucleotide exchange factor). Here we report the crystal structure of the complex between Sar1 and the...