9.B.196 The Integral Membrane Phosphodiesterase, PAP2 or PgpB (PAP2) Family
The PAP2 family consists of numerous integral membrane proteins, correctly annotated in Pfam and NCBI as phosphodiesterases. Phosphatidylcholine (PC) hydrolysis generates two important second messengers: phosphatidic acid (PA) and diacylglycerol (DAG). Phospholipase D (PLD) and phosphatidate phosphohydrolase (PAPase) are involved in their generation and therefore are key enzymes in signal transduction. Specific isoforms of these enzymes are activated by receptor occupancy in the brain. Phosphatidylinositol 4,5-bisphosphate-dependent PLD (PIP2-PLD) and N-ethylmaleimide-insensitive PAPase (PAP2) have been suggested to act in series to generate the biologically active lipids PA and DAG (Salvador et al. 2002; ).