Coenzyme A functions as an acyl group carrier, acetyl-CoA. Phenylacetyl coenzyme A (Phenylacetyl-CoA) is used to study the mechanism of action of the TetR family transcriptional repressor PaaR. Phenylacetyl-CoA is used to study the phenylacetyl-CoA monooxygenase complex found in bacteria such as E. coli.