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spinqualitylabelsall models 1m2o, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal Structure of the Sec23-Sar1 complex

Overview

COPII-coated vesicles form on the endoplasmic reticulum by the stepwise recruitment of three cytosolic components: Sar1-GTP to initiate coat formation, Sec23/24 heterodimer to select SNARE and cargo molecules, and Sec13/31 to induce coat polymerization and membrane deformation. Crystallographic analysis of the Saccharomyces cerevisiae Sec23/24-Sar1 complex reveals a bow-tie-shaped structure, 15 nm long, with a membrane-proximal surface that is concave and positively charged to conform to the size and acidic-phospholipid composition of the COPII vesicle. Sec23 and Sar1 form a continuous surface stabilized by a non-hydrolysable GTP analogue, and Sar1 has rearranged from the GDP conformation to expose amino-terminal residues that will probably embed in the bilayer. The GTPase-activating protein (GAP) activity of Sec23 involves an arginine side chain inserted into the Sar1 active site. These observations establish the structural basis for GTP-dependent recruitment of a vesicular coat complex, and for uncoating through coat-controlled GTP hydrolysis.

About this Structure

1M2O is a Protein complex structure of sequences from Saccharomyces cerevisiae with , and as ligands. Full crystallographic information is available from OCA.

Reference

Structure of the Sec23/24-Sar1 pre-budding complex of the COPII vesicle coat., Bi X, Corpina RA, Goldberg J, Nature. 2002 Sep 19;419(6904):271-7. PMID:12239560

Page seeded by OCA on Thu Feb 21 13:50:54 2008