 For example, palmitoylation of phospholipase D (PLD) sequesters the enzyme away from its substrate phosphatidylcholine.When cholesterol levels decrease or PIP2 levels increase the palmitate mediated localization is disrupted, the enzyme trafficks to PIP2 where it encounters its substrate and is active by substrate presentation.Scientists have appreciated the significance of attaching long hydrophobic chains to specific proteins in cell signaling pathways.