Exo1

Exo1 inhibits traffic emanating from the endoplasmic reticulum by inducing rapid collapse of the Golgi to the endoplasmic reticulum1. Like Brefeldin A, Exo1 induces the rapid release of ARF1 from Golgi membranes, but evidence suggests that Exo1 acts by a different mechanism. Exo1 does not induce the ADP-ribosylation of CtBP/Bars50, and does not interfere with the activity of guanine nucleotide exchange factors specific for Golgi-based ARFs, allowing Exo1 to be used as a tool for differentiating the fatty acid exchange activity of Bars50 from ARF1 activity.