1cip
From Proteopedia
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GI-ALPHA-1 SUBUNIT OF GUANINE NUCLEOTIDE-BINDING PROTEIN COMPLEXED WITH A GTP ANALOGUE
Overview
The structure of the G protein Gialpha1 complexed with the nonhydrolyzable, GTP analog guanosine-5'-(betagamma-imino)triphosphate (GppNHp) has been, determined at a resolution of 1.5 A. In the active site of Gialpha1., GppNHp, a water molecule is hydrogen bonded to the side chain of Glu43 and, to an oxygen atom of the gamma-phosphate group. The side chain of the, essential catalytic residue Gln204 assumes a conformation which is, distinctly different from that observed in complexes with either guanosine, 5'-O-3-thiotriphosphate or the transition state analog GDP.AlF4-. Hydrogen, bonding and steric interactions position Gln204 such that it interacts, with a presumptive nucleophilic water molecule, but cannot interact with, the pentacoordinate transition state. Gln204 must be released from this, auto-inhibited state to participate in catalysis. RGS proteins may, accelerate the rate of GTP hydrolysis by G protein alpha subunits, in, part, by inserting an amino acid side chain into the site occupied by, Gln204, thereby destabilizing the auto-inhibited state of Galpha.
About this Structure
1CIP is a Single protein structure of sequence from Rattus norvegicus with MG and GNP as ligands. Full crystallographic information is available from OCA.
Reference
Structure of Gialpha1.GppNHp, autoinhibition in a galpha protein-substrate complex., Coleman DE, Sprang SR, J Biol Chem. 1999 Jun 11;274(24):16669-72. PMID:10358003
Page seeded by OCA on Tue Nov 20 12:29:37 2007
Categories: Rattus norvegicus | Single protein | Coleman, D. | Sprang, S. | GNP | MG | G protein | Gtpase
