A paxillin tyrosine phosphorylation switch regulates the assembly and form of cell-matrix adhesions

Ronen Zaidel-Bar, Ron Milo, Zvi Kam, Benjamin Geiger

Research output: Contribution to journalArticlepeer-review


Diverse cellular processes are carried out by distinct integrin-mediated adhesions. Cell spreading and migration are driven by focal complexes; robust adhesion to the extracellular matrix by focal adhesions; and matrix remodeling by fibrillar adhesions. The mechanism(s) regulating the spatio-temporal distribution and dynamics of the three types of adhesion are unknown. Here, we combine live-cell imaging, labeling with phosphospecific-antibodies and overexpression of a novel tyrosine phosphomimetic mutant of paxillin, to demonstrate that the modulation of tyrosine phosphorylation of paxillin regulates both the assembly and turnover of adhesion sites. Moreover, phosphorylated paxillin enhanced lamellipodial protrusions, whereas non-phosphorylated paxillin was essential for fibrillar adhesion formation and for fibronectin fibrillogenesis. We further show that focal adhesion kinase preferentially interacted with the tyrosine phosphomimetic paxillin and its recruitment is implicated in high turnover of focal complexes and translocation of focal adhesions. We created a mathematical model that recapitulates the salient features of the measured dynamics, and conclude that tyrosine phosphorylation of the adaptor protein paxillin functions as a major switch, regulating the adhesive phenotype of cells.

Original languageEnglish
Pages (from-to)137-148
Number of pages12
JournalJournal of Cell Science
Issue number1
StatePublished - 1 Jan 2007
Externally publishedYes


  • Adhesion dynamics
  • Cell-matrix adhesion
  • Fibrillar adhesions
  • Fibronectin
  • Focal adhesions
  • Focal complexes
  • Paxillin
  • Phosphomimetic
  • Tyrosine phosphorylation


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