PDMP blocks the BFA-induced ADP-ribosylation of BARS-50 in isolated Golgi membranes

We reported that an inhibitor of sphingolipid biosynthesis, D,L-threo-1-phe nyl-2-decanoylamino-3-morpholinol-1-propanol (PDMP), blocks brefeldin A (BF A)-induced retrograde membrane transport from the Golgi complex to the endo plasmic reticulum (ER) (Kok et al,, 1998, J. Cell Biol. 142, 25-38), We now show that PDMP partially blocks the BFA-induced ADP-ribosylation of the cy tosolic protein BARS-50. Moreover, PDMP does not interfere with the BFA-ind uced inhibition of the binding of ADP-ribosylation factor (ARF) and the coa tomer component p-coat protein to Golgi membranes, These results are consis tent with a role of ADP-ribosylation in the action of BFA and with the invo lvement of BARS-50 in the regulation of membrane trafficking. (C) 1999 Fede ration of European Biochemical Societies.