The nature of the globular- to fibrous-actin transition

Nature. 2009 Jan 22;457(7228):441-5. doi: 10.1038/nature07685.


Actin plays crucial parts in cell motility through a dynamic process driven by polymerization and depolymerization, that is, the globular (G) to fibrous (F) actin transition. Although our knowledge about the actin-based cellular functions and the molecules that regulate the G- to F-actin transition is growing, the structural aspects of the transition remain enigmatic. We created a model of F-actin using X-ray fibre diffraction intensities obtained from well oriented sols of rabbit skeletal muscle F-actin to 3.3 A in the radial direction and 5.6 A along the equator. Here we show that the G- to F-actin conformational transition is a simple relative rotation of the two major domains by about 20 degrees. As a result of the domain rotation, the actin molecule in the filament is flat. The flat form is essential for the formation of stable, helical F-actin. Our F-actin structure model provides the basis for understanding actin polymerization as well as its molecular interactions with actin-binding proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / chemistry*
  • Actins / metabolism*
  • Animals
  • Biopolymers / chemistry
  • Biopolymers / metabolism
  • Cell Movement
  • Glutamine / metabolism
  • Hydrolysis
  • Magnetics
  • Models, Molecular
  • Muscle Contraction
  • Muscle, Skeletal / chemistry
  • Protein Structure, Quaternary
  • Protein Subunits / chemistry
  • Protein Subunits / metabolism
  • Rabbits
  • X-Ray Diffraction


  • Actins
  • Biopolymers
  • Protein Subunits
  • Glutamine

Associated data

  • PDB/2ZWH