Phospholipase D is associated in a phorbol ester-dependent manner with protein kinase c-α and with a 220-kDa protein which is phosphorylated on serine and threonine

Many studies have shown that phospholipase D (PLD) is activated by protein kinase C (PKC) in vivo and in vitro. In this study, a PLD isoform (rPLD1) was shown to bind to PKC-α in Rat1 fibroblasts treated with phorbol ester. The PKC-α binding domain of rPLD1 was localized to its N-terminus. The phospholipase was shown to become associated also with a 220 kDa protein (p220) in the fibroblasts and in Sf9 cells infected with recombinant baculovirus coding rPLD1. This interaction was increased by phorbol myristate acetate (PMA) treatment. p220 was phosphorylated on serine/threonine in PMA-stimulated Rat1 cells, and rPLD1 expressed in Sf9 cells was also serine/threonine phosphorylated in response to PMA treatment. These data suggest the PMA induces the formation of a RPLD1/PKCα/P220 complex in cells, some components of which undergo serine/threonine phosphorylation.