How a G protein binds a membrane

J Biol Chem. 2004 Aug 6;279(32):33937-45. doi: 10.1074/jbc.M403404200. Epub 2004 Jun 1.


Heterotrimeric G proteins interact with receptors and effectors at the membrane-cytoplasm interface. Structures of soluble forms have not revealed how they interact with membranes. We have used electron crystallography to determine the structure in ice of a helical array of the photoreceptor G protein, transducin, bound to the surface of a tubular lipid bilayer. The protein binds to the membrane with a very small area of contact, restricted to two points, between the surface of the protein and the surface of the lipids. Fitting the x-ray structure into the membrane-bound structure reveals one membrane contact near the lipidated Ggamma C terminus and Galpha N terminus, and another near the Galpha C terminus. The narrowness of the tethers to the lipid bilayer provides flexibility for the protein to adopt multiple orientations on the membrane, and leaves most of the G protein surface area available for protein-protein interactions.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Binding Sites
  • Cattle
  • Cell Membrane / metabolism*
  • Crystallization
  • Crystallography, X-Ray
  • Ice
  • Image Processing, Computer-Assisted
  • Lipid Bilayers / chemistry
  • Lipid Bilayers / metabolism
  • Membrane Lipids / chemistry
  • Membrane Lipids / metabolism
  • Microscopy, Electron
  • Models, Molecular
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Protein Binding
  • Protein Structure, Secondary
  • Rod Cell Outer Segment / chemistry
  • Transducin / chemistry*
  • Transducin / metabolism*


  • Ice
  • Lipid Bilayers
  • Membrane Lipids
  • Peptide Fragments
  • Transducin