Dynamic Coupling and Allosteric Networks in the α Subunit of Heterotrimeric G Proteins

J Biol Chem. 2016 Feb 26;291(9):4742-53. doi: 10.1074/jbc.M115.702605. Epub 2015 Dec 24.


G protein α subunits cycle between active and inactive conformations to regulate a multitude of intracellular signaling cascades. Important structural transitions occurring during this cycle have been characterized from extensive crystallographic studies. However, the link between observed conformations and the allosteric regulation of binding events at distal sites critical for signaling through G proteins remain unclear. Here we describe molecular dynamics simulations, bioinformatics analysis, and experimental mutagenesis that identifies residues involved in mediating the allosteric coupling of receptor, nucleotide, and helical domain interfaces of Gαi. Most notably, we predict and characterize novel allosteric decoupling mutants, which display enhanced helical domain opening, increased rates of nucleotide exchange, and constitutive activity in the absence of receptor activation. Collectively, our results provide a framework for explaining how binding events and mutations can alter internal dynamic couplings critical for G protein function.

Keywords: G protein; allosteric regulation; bioinformatics; molecular dynamics; mutagenesis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allosteric Regulation
  • Amino Acid Substitution
  • Animals
  • Binding Sites
  • Cattle
  • Computational Biology
  • Databases, Protein
  • GTP-Binding Protein alpha Subunits / chemistry*
  • GTP-Binding Protein alpha Subunits / genetics
  • GTP-Binding Protein alpha Subunits / metabolism
  • HEK293 Cells
  • Humans
  • Ligands
  • Mice
  • Models, Molecular*
  • Molecular Dynamics Simulation
  • Mutagenesis, Site-Directed
  • Mutant Proteins / chemistry
  • Mutant Proteins / metabolism
  • Principal Component Analysis
  • Protein Conformation
  • Protein Unfolding
  • Rats
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Sf9 Cells


  • GTP-Binding Protein alpha Subunits
  • Ligands
  • Mutant Proteins
  • Recombinant Proteins

Associated data

  • PDB/1KJY
  • PDB/1TAG
  • PDB/1TND