Active Arf6 recruits ARNO/cytohesin GEFs to the PM by binding their PH domains

Lee Ann Cohen, Akira Honda, Peter Varnai, Fraser D. Brown, Tamas Balla, Julie G. Donaldson

Research output: Contribution to journalArticle

152 Citations (Scopus)


ARNO is a soluble guanine nucleotide exchange factor (GEF) for the Arf family of GTPases. Although in biochemical assays ARNO prefers Arf1 over Arf6 as a substrate, its localization in cells at the plasma membrane (PM) suggests an interaction with Arf6. In this study, we found that ARNO activated Arf1 in HeLa and COS-7 cells resulting in the recruitment of Arf1 on to dynamic PM ruffles. By contrast, Arf6 was activated less by ARNO than EFA6, a canonical Arf6 GEF. Remarkably, Arf6 in its GTP-bound form recruited ARNO to the PM and the two proteins could be immunoprecipitated. ARNO binding to Arf6 was not mediated through the catalytic Sec7 domain, but via the pleckstrin homology (PH) domain. Active Arf6 also bound the PH domain of Grp1, another ARNO family member. This interaction was direct and required both inositol phospholipids and GTP. We propose a model of sequential Arf activation at the PM whereby Arf6-GTP recruits ARNO family GEFs for further activation of other Arf isoforms.

Original languageEnglish
Pages (from-to)2244-2253
Number of pages10
JournalMolecular Biology of the Cell
Issue number6
Publication statusPublished - Jun 1 2007

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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