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Biochemistry. 2012 Aug 21;51(33):6644-53. doi: 10.1021/bi300722t. Epub 2012 Aug 10.

Arg/Abl2 modulates the affinity and stoichiometry of binding of cortactin to F-actin.

Author information

1
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.

Abstract

The Abl family nonreceptor tyrosine kinase Arg/Abl2 interacts with cortactin, an Arp2/3 complex activator, to promote actin-driven cell edge protrusion. Both Arg and cortactin bind directly to filamentous actin (F-actin). While protein-protein interactions between Arg and cortactin have well-characterized downstream effects on the actin cytoskeleton, it is unclear whether and how Arg and cortactin affect each other's actin binding properties. We employ actin cosedimentation assays to show that Arg increases the stoichiometry of binding of cortactin to F-actin at saturation. Using a series of Arg deletion mutants and fragments, we demonstrate that the Arg C-terminal calponin homology domain is necessary and sufficient to increase the stoichiometry of binding of cortactin to F-actin. We also show that interactions between Arg and cortactin are required for optimal affinity between cortactin and the actin filament. Our data suggest a mechanism for Arg-dependent stimulation of binding of cortactin to F-actin, which may facilitate the recruitment of cortactin to sites of local actin network assembly.

PMID:
22849492
PMCID:
PMC3556572
DOI:
10.1021/bi300722t
[Indexed for MEDLINE]
Free PMC Article

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