An oleate dependent form of phospholipase D is present in rat brain neuronal nuclei and both the hydrolytic and transphosphatidylation activities measured. Several acidic phospholipids were found to inhibit this activity in a dose dependent manner. The IC50 values varied from 3.5 microM for PIP2 to 200 microM for phosphatidic acid. The hydrolysis of PIP2 by phospholipase C would be expected to result in the disinhibition of the oleate dependent phospholipase D activity.