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Updated: Jul 19, 2026

Aip1p Dynamics Are Altered by the R256H Mutation in Actin
Published on: July 30, 2014
ARAP2 effects on the actin cytoskeleton are dependent on Arf6-specific GTPase-activating-protein activity and binding
Hye-Young Yoon1, Koichi Miura, E Jebb Cuthbert
1Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Department of Health and Human Services, Building 37, Bethesda, MD 20892, USA.
Abstract:
ARAP2 is a protein that contains both ArfGAP and RhoGAP domains. We found that it is a phosphatidylinositol (3,4,5)-trisphosphate-dependent Arf6 GAP that binds RhoA-GTP but lacks RhoGAP activity. In agreement with the hypothesis that ARAP2 mediates effects of RhoA, endogenous ARAP2 associated with focal adhesions (FAs) and reduction of ARAP2 expression, by RNAi, resulted in fewer FAs and actin stress fibers (SFs). In cells with reduced levels of endogenous ARAP2, FAs and SFs could be restored with wild-type recombinant ARAP2 but not mutants lacking ArfGAP or Rho-binding activity. Constitutively active Arf6 also caused a loss of SFs. The Rho effector ROKalpha was ineffective in restoring FAs. Conversely, overexpression of ARAP2 did not restore SFs in cells treated with a ROK inhibitor but induced punctate accumulations of paxillin. We conclude that ARAP2 is an Arf6GAP that functions downstream of RhoA to regulate focal adhesion dynamics.
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