1M2O

Crystal Structure of the Sec23-Sar1 complex

Summary for 1M2O

• Entry DOI: 10.2210/pdb1m2o/pdb
• Related: 1M2V
• Descriptor: protein transport protein SEC23, GTP-binding protein SAR1, ZINC ION, ... (6 entities in total)
• Functional Keywords: zinc-finger, beta barrel, vwa domain, gelsolin domain, protein transport-signaling protein complex, protein transport/signaling protein
• Biological source: Saccharomyces cerevisiae (baker's yeast); More
• Cellular location: Cytoplasm: P15303; Cytoplasmic vesicle, COPII-coated vesicle membrane; Peripheral membrane protein; Cytoplasmic side: P20606
• Total number of polymer chains: 4
• Total formula weight: 215095.43

Authors

Bi, X.,Corpina, R.A.,Goldberg, J. (deposition date: 2002-06-24, release date: 2002-09-20, Last modification date: 2024-02-14)

Primary citation

Bi, X.,Corpina, R.A.,Goldberg, J.
Structure of the Sec23/24-Sar1 pre-budding complex of the COPII vesicle coat
Nature, 419:271-277, 2002

PubMed Abstract: 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.

PubMed: 12239560
DOI: 10.1038/nature01040

Experimental method

X-RAY DIFFRACTION (2.5 Å)