Filamin is essential in actin cytoskeletal assembly mediated by p21-activated kinase 1

Nat Cell Biol. 2002 Sep;4(9):681-90. doi: 10.1038/ncb838.


The serine/threonine kinase p21-activated kinase 1 (Pak1) controls the actin cytoskeletal and ruffle formation through mechanisms that are independent of GTPase activity. Here we identify filamin FLNa as a Pak1-interacting protein through a yeast two-hybrid screen using the amino terminus of Pak1 as a bait. FLNa is stimulated by physiological signalling molecules to undergo phosphorylation by Pak1 and to interact and colocalize with endogenous Pak1 in membrane ruffles. The ruffle-forming activity of Pak1 is functional in FLNa-expressing cells but not in FLNa-deficient cells. In FLNa, the Pak1-binding site involves tandem repeat 23 in the carboxyl terminus and phosphorylation takes place on serine 2152. The FLNa-binding site in Pak1 is localized between amino acids 52 and 132 in the conserved Cdc42/Rac-interacting (CRIB) domain; accordingly, FLNa binding to the CRIB domain stimulates Pak1 kinase activity. Our results indicate that FLNa may be essential for Pak1-induced cytoskeletal reorganization and that the two-way regulatory interaction between Pak1 and FLNa may contribute to the local stimulation of Pak1 activity and its targets in cytoskeletal structures.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism*
  • Binding Sites
  • Cell Line
  • Contractile Proteins / chemistry
  • Contractile Proteins / genetics
  • Contractile Proteins / metabolism*
  • Cytoskeleton / metabolism
  • Cytoskeleton / ultrastructure
  • Enzyme Activation
  • Filamins
  • Green Fluorescent Proteins
  • Humans
  • In Vitro Techniques
  • Lim Kinases
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Microfilament Proteins / chemistry
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Mitogen-Activated Protein Kinases / metabolism
  • Mutation
  • Phosphorylation
  • Protein Kinases / metabolism
  • Protein-Serine-Threonine Kinases / chemistry
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Signal Transduction
  • Substrate Specificity
  • Two-Hybrid System Techniques
  • p21-Activated Kinases


  • Actins
  • Contractile Proteins
  • Filamins
  • Luminescent Proteins
  • Microfilament Proteins
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins
  • Protein Kinases
  • LIMK1 protein, human
  • Lim Kinases
  • PAK1 protein, human
  • Protein-Serine-Threonine Kinases
  • p21-Activated Kinases
  • Mitogen-Activated Protein Kinases