The inhibitor Endosidin 4 targets SEC7 domain-type ARF GTPase exchange factors and interferes with subcellular trafficking ($) (Plant Cell)

Subcellular trafficking helps determine the development of the plant through for instance the regulation of polar localization of auxin transporter PIN-FORMED (PIN) proteins. PIN trafficking or recycling is maintained by GNOM, a BFA-sensitive ARF GEF (ADP-ribosylation factor guanine nucleotide exchange factor). Much of what we know about ARF-GEFs comes from studies using the fungal inhibitor Brefeldin A (BFA). BFA inhibits most of the ARF GEFs, except GNL1 and BIG3. In this work, the authors used a chemical genetics approach and identified Endosidin 4 (ES4) as an inhibitor of ARF/ARF GEF-dependent pathway. ES4 interrupts endosomal protein trafficking by targeting SEC7-domain containing ARF GEFs. ES4 will help to dissect unknown functional roles of ARF GEFs for plant development. (See also this companion paper describing the characterization of another ARF GEF inhibitor, Secdin). (Summary by Arif Ashraf) Plant Cell: 10.1105/tpc.18.00127