3FFB

Gi-alpha-1 mutant in GDP bound form


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.57 Å
  • R-Value Free: 0.226 
  • R-Value Work: 0.181 

Starting Model: experimental
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This is version 1.3 of the entry. See complete history


Literature

Structural evidence for a sequential release mechanism for activation of heterotrimeric g proteins.

Kapoor, N.Menon, S.T.Chauhan, R.Sachdev, P.Sakmar, T.P.

(2009) J Mol Biol 393: 882-897

  • DOI: https://doi.org/10.1016/j.jmb.2009.08.043
  • Primary Citation of Related Structures:  
    3FFA, 3FFB

  • PubMed Abstract: 

    Heptahelical G-protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptors couple to heterotrimeric G proteins to relay extracellular signals to intracellular signaling networks, but the molecular mechanism underlying guanosine 5'-diphosphate (GDP) release by the G protein alpha-subunit is not well understood. Amino acid substitutions in the conserved alpha5 helix of G(i), which extends from the C-terminal region to the nucleotide-binding pocket, cause dramatic increases in basal (receptor-independent) GDP release rates. For example, mutant Galpha(i1)-T329A shows an 18-fold increase in basal GDP release rate and, when expressed in culture, it causes a significant decrease in forskolin-stimulated cAMP accumulation. The crystal structure of Galpha(i1)-T329A.GDP shows substantial conformational rearrangement of the switch I region and additional striking alterations of side chains lining the catalytic pocket that disrupt the Mg(+2) coordination sphere and dislodge bound Mg(+2). We propose a "sequential release" mechanism whereby a transient conformational change in the alpha5 helix alters switch I to induce GDP release. Interestingly, this mechanistic model for heterotrimeric G protein activation is similar to that suggested for the activation of the plant small G protein Rop4 by RopGEF8.


  • Organizational Affiliation

    Laboratory of Biochemistry and Molecular Biology, Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Guanine nucleotide-binding protein G(i), alpha-1 subunit360Rattus norvegicusMutation(s): 1 
Gene Names: Gi-alpha-1Gnai-1Gnai1
EC: 3.6.5
UniProt
Find proteins for P10824 (Rattus norvegicus)
Explore P10824 
Go to UniProtKB:  P10824
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP10824
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.57 Å
  • R-Value Free: 0.226 
  • R-Value Work: 0.181 
  • Space Group: I 4
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 121.761α = 90
b = 121.761β = 90
c = 68.714γ = 90
Software Package:
Software NamePurpose
ADSCdata collection
PHASERphasing
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-10-06
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2021-10-20
    Changes: Database references, Derived calculations
  • Version 1.3: 2023-09-06
    Changes: Data collection, Refinement description