The replacement of the sn-1 and sn-2 carbonyl esters in DAG-surrogate lactones by sulfonate esters showed that their isosteric properties in protein kinase C binding are controlled by the location of the hydrophobic alkyl chain on the molecule. The CO and SO2 groups appear to be true isosteres only when they are adjacent to the alkyl chain, which is presumed to insert normal to the lipid bilayer.