FAS generates an endogenous ligand for PPARα in liver. FAS, a homodimer, synthesizes palmitate, which is converted to a CoA species that is incorporated into diacylglycerol (DAG). CDP-choline is generated by the sequential actions of CK (choline kinase) and CCT (CTP:phosphocholine cytidylyltransferase), enzymes in the Kennedy pathway of phosphatidylcholine synthesis. DAG and CDP-choline are converted by the ER protein choline-ethanolamine phosphotransferase-1 (CEPT1) to 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine. This phosphatidylcholine species binds to PPARα, which forms a heterodimer with RXR to activate gene expression.