PLD2 has 51% sequence identity to PLD1 and possesses the same four conserved sequences. It has high intrinsic activity, is unaffected by PKC isozymes and Rho proteins, and shows little activation by ARF. However, if the first 308 amino acids are deleted, the basal activity of the enzyme decreases markedly and it becomes very responsive to ARF, but not other stimulators. As noted in Section 5.1., the subcellular distribution of PLD2 differs from that of PLD1, that is, it localizes primarily to the plasma membrane and components of the actin cytoskeleton. Serum stimulation of fibroblasts expressing PLD2 causes redistribution of the enzyme from the plasma membrane to submembranous vesicles and the formation of filo-podia-like projections indicative of reorganization of the actin cytoskeleton. PL2 is inhibited by two proteins (a- and P-synucleins) that are associated with synaptic membranes. These proteins do not affect PLD1 activity, and their action on PLD2 is not overcome by PIP2or activators of PLD1.
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