Paxillin dynamics measured during adhesion assembly and disassembly by correlation spectroscopy

Biophys J. 2008 Apr 1;94(7):2819-31. doi: 10.1529/biophysj.107.104984. Epub 2007 Nov 9.


Paxillin is an adaptor molecule involved in the assembly of focal adhesions. Using different fluorescence fluctuation approaches, we established that paxillin-EGFP is dynamic on many timescales within the cell, ranging from milliseconds to seconds. In the cytoplasmic regions, far from adhesions, paxillin is uniformly distributed and freely diffusing as a monomer, as determined by single-point fluctuation correlation spectroscopy and photon-counting histogram analysis. Near adhesions, paxillin dynamics are reduced drastically, presumably due to binding to protein partners within the adhesions. The photon-counting histogram analysis of the fluctuation amplitudes reveals that this binding equilibrium in new or assembling adhesions is due to paxillin monomers binding to quasi-immobile structures, whereas in disassembling adhesions or regions of adhesions, the equilibrium is due to exchange of large aggregates. Scanning fluctuation correlation spectroscopy and raster-scan image correlation spectroscopy analysis of laser confocal images show that the environments within adhesions are heterogeneous. Relatively large adhesions appear to slide transversally due to a treadmilling mechanism through the addition of monomeric paxillin at one side and removal of relatively large aggregates of proteins from the retracting edge. Total internal reflection microscopy performed with a fast acquisition EM-CCD camera completes the overall dynamic picture and adds details of the heterogeneous dynamics across single adhesions and simultaneous bursts of activity at many adhesions across the cell.

Publication types

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

MeSH terms

  • Animals
  • CHO Cells
  • Cell Adhesion / physiology*
  • Cricetinae
  • Cricetulus
  • Dimerization
  • Multiprotein Complexes / chemistry
  • Multiprotein Complexes / physiology
  • Multiprotein Complexes / ultrastructure
  • Paxillin / chemistry*
  • Paxillin / physiology*
  • Paxillin / ultrastructure
  • Spectrometry, Fluorescence / methods*


  • Multiprotein Complexes
  • Paxillin