1g17
From Proteopedia
|
CRYSTAL STRUCTURE OF SEC4-GUANOSINE-5'-(BETA,GAMMA)-IMIDOTRIPHOSPHATE
Overview
We have determined crystal structures of Sec4, a member of the Rab family, in the G protein superfamily, in two states: bound to GDP, and to a, non-hydrolyzable GTP analog, guanosine-5'-(beta, gamma)-imidotriphosphate, (GppNHp). This represents the first structure of a Rab protein bound to, GDP. Sec4 in both states grossly resembles other G proteins bound to GDP, and GppNHp. In Sec4-GppNHp, structural features common to active Rab, proteins are observed. In Sec4-GDP, the switch I region is highly, disordered and displaced relative to the switch I region of Ras-GDP. In, two of the four molecules of Sec4-GDP in the asymmetric unit of the, Sec4-GDP crystals, the switch II region adopts a conformation similar to, that seen in the structure of the small G protein Ran bound to GDP. This, allows residues threonine 76, glutamate 80, and arginine 81 of Sec4 to, make contacts with other conserved residues and water molecules important, for nucleotide binding. In the other two molecules in the asymmetric unit, these interactions do not take place. This structural variability in both, the switch I and switch II regions of GDP-bound Sec4 provides a possible, explanation for the high off-rate of GDP bound to Sec4, and suggests a, mechanism for regulation of the GTPase cycle of Rab proteins by GDI, proteins.
About this Structure
1G17 is a Single protein structure of sequence from Saccharomyces cerevisiae with MG and GNP as ligands. Full crystallographic information is available from OCA.
Reference
Crystal structures of a Rab protein in its inactive and active conformations., Stroupe C, Brunger AT, J Mol Biol. 2000 Dec 8;304(4):585-98. PMID:11099382
Page seeded by OCA on Tue Nov 20 15:36:51 2007
