Aip1p interacts with cofilin to disassemble actin filaments

J Cell Biol. 1999 Jun 14;145(6):1251-64. doi: 10.1083/jcb.145.6.1251.


Actin interacting protein 1 (Aip1) is a conserved component of the actin cytoskeleton first identified in a two-hybrid screen against yeast actin. Here, we report that Aip1p also interacts with the ubiquitous actin depolymerizing factor cofilin. A two-hybrid-based approach using cofilin and actin mutants identified residues necessary for the interaction of actin, cofilin, and Aip1p in an apparent ternary complex. Deletion of the AIP1 gene is lethal in combination with cofilin mutants or act1-159, an actin mutation that slows the rate of actin filament disassembly in vivo. Aip1p localizes to cortical actin patches in yeast cells, and this localization is disrupted by specific actin and cofilin mutations. Further, Aip1p is required to restrict cofilin localization to cortical patches. Finally, biochemical analyses show that Aip1p causes net depolymerization of actin filaments only in the presence of cofilin and that cofilin enhances binding of Aip1p to actin filaments. We conclude that Aip1p is a cofilin-associated protein that enhances the filament disassembly activity of cofilin and restricts cofilin localization to cortical actin patches.

Publication types

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

MeSH terms

  • Actin Depolymerizing Factors
  • Actins / analysis
  • Actins / antagonists & inhibitors
  • Actins / genetics
  • Actins / metabolism*
  • Amino Acid Sequence
  • Antibodies
  • Binding Sites
  • Cloning, Molecular
  • Cytoskeleton / metabolism*
  • Fungal Proteins / analysis
  • Fungal Proteins / chemistry
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Genes, Lethal / genetics
  • Kinetics
  • Microfilament Proteins / analysis
  • Microfilament Proteins / chemistry
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Polymers / metabolism
  • Protein Binding
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Thermodynamics


  • Actin Depolymerizing Factors
  • Actins
  • Antibodies
  • Fungal Proteins
  • Microfilament Proteins
  • Polymers
  • actin interacting protein 1