1cip | pdb_00001cip
GI-ALPHA-1 SUBUNIT OF GUANINE NUCLEOTIDE-BINDING PROTEIN COMPLEXED WITH A GTP ANALOGUE
Structural highlights
Function[GNAI1_RAT] Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. The G(i) proteins are involved in hormonal regulation of adenylate cyclase: they inhibit the cyclase in response to beta-adrenergic stimuli. The inactive GDP-bound form prevents the association of RGS14 with centrosomes and is required for the translocation of RGS14 from the cytoplasm to the plasma membrane. May play a role in cell division.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe 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. 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[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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