Palmitoyl Protein Thioesterase 2 (PPT2)

The deduced PPT2 protein contains 302 amino acids, including a 27-amino acid leader peptide, a sequence motif characteristic of many thioesterases and lipases, and 5 potential N-linked glycosylation sites. PPT2 shares 18% amino acid identity with PPT1. Treatment that removes asparagine-linked oligosaccharides resulted in a single major protein of 31 kD and a minor protein of 33 kD. The authors demonstrated that recombinant PPT2, like PPT1, possesses thioesterase activity and localizes to the lysosome. Since PPT2 could not substitute for PPT1 in correcting the metabolic defect in CLN2 cells and was unable to remove palmitate groups from palmitoylated proteins that are routinely used as substrates for PPT1, PPT2 possesses a different substrate specificity than PPT1.