Interactions with PIP2, ADP-actin monomers, and capping protein regulate the activity and localization of yeast twinfilin

Citation
S. Palmgren et al., Interactions with PIP2, ADP-actin monomers, and capping protein regulate the activity and localization of yeast twinfilin, J CELL BIOL, 155(2), 2001, pp. 251-260
Citations number
38
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell & Developmental Biology
Journal title
JOURNAL OF CELL BIOLOGY
ISSN journal
0021-9525 → ACNP
Volume
155
Issue
2
Year of publication
2001
Pages
251 - 260
Database
ISI
SICI code
0021-9525(20011015)155:2<251:IWPAMA>2.0.ZU;2-Z
Abstract
Twinfilin is a ubiquitous actin monomer-binding protein that regulates acti n filament turnover in yeast and mammalian cells. To elucidate the mechanis m by which twinfilin contributes to actin filament dynamics, we carried out an analysis of yeast twinfilin, and we show here that twinfilin is an abun dant protein that localizes to cortical actin patches in wild-type yeast ce lls. Native gel assays demonstrate that twinfilin binds ADP-actin monomers with higher affinity than ATP-actin monomers. A mutant twinfilin that does not interact with actin monomers in vitro no longer localizes to cortical a ctin patches when expressed in yeast, suggesting that the ability to intera ct with actin monomers may be essential for the localization of twinfilin. The localization of twinfilin to the cortical actin cytoskeleton is also di srupted in yeast strains where either the CAP1 or CAP2 gene, encoding for t he alpha and beta subunits of capping protein, is deleted. Purified twinfil in and capping protein form a complex on native gels. Twinfilin also intera cts with phosphatidylinositol 4,5-bisphosphate (PI[4,5]P-2), and its actin monomer-sequestering activity is inhibited by PI(4,5)P-2. Based on these re sults, we propose a model for the biological role of twinfilin as a protein that localizes actin monomers to the sites of rapid filament assembly in c ells.