Arf1-GDP Arf1-GTP Arf1 Activation by GBF1 Authored: Gillespie, ME, 2007-07-23 15:44:13 Pubmed10402461 Reactome Database ID Release 43199998 Reactome, http://www.reactome.org ReactomeREACT_11099 Reviewed: Rush, MG, 2008-01-11 00:00:00 The formation of the COPI coat requires membrane recruitment and activation of Arf1. Arf1 activation is normally mediated by guanine nucleotide exchange factors (GEFs) that convert Arf1 to its active GTP-bound state on the membrane. In this reaction that GEF is represented by GBF1.