Arfaptin 1 forms a complex with ADP-ribosylation factor and inhibits phospholipase D

ADP-ribosylation factors (ARFs) regulate coatomer assembly on the Golgi as well as recruitment of clathrin adapter proteins and are therefore involved in vesicle budding from the Golgi and vesicular transport. They are also r egulators of phospholipase D (PLD) activity, Arfaptin 1 is an ARF binding p rotein that inhibits PLD activation, vesicular trafficking and secretion. I n the present report, we show that arfaptin 1 interacts with 'high speed' m embranes independently of ARF, However, addition of myristoylated ARF3 (myr ARF3) increases the association of arfaptin 1 with the membranes, suggestin g that arfaptin 1 and ARF form a complex on the Golgi, Utilizing several de letion mutants of arfaptin 1 it is shown that the association of arfaptin 1 with myrARF3 is mediated via two binding sites on arfaptin 1, These two do mains are needed for arfaptin 1 inhibition of PLD activation by myrARF3 in vitro. (C) 1999 Federation of European Biochemical Societies.