Thioesterase II (TEII) is thought to regenerate misprimed nonribosomal peptide synthetases (NRPSs) as well as modular polyketide synthases (PKSs) by hydrolyzing acetyl groups bound to the peptidyl carrier protein (PCP) and acyl carrier protein (ACP) domains, respectively. TEII has two tandem asymmetric hot dog folds that are structurally similar to one found in PaaI thioesterase, 4-hydroxybenzoyl-CoA thioesterase (4HBT) and beta-hydroxydecanoyl-ACP dehydratase and thus, the TEII monomer is equivalent to the homodimeric form of the latter three enzymes. Human TEII is expressed in T cells and has been shown to bind the product of the HIV-1 Nef gene.