Has thioesterase activity against fatty acid thioesters with 14 -18 carbons, including palmitoyl-CoA, S-palmitoyl-N- acetylcysteamine, and palmitoylated proteins (PubMed:12855696, PubMed:26731412, PubMed:8816748). In contrast to PPT2, PPT1 can hydrolyze palmitoylated proteins and palmitoylcysteine (PubMed:12855696). {ECO:0000269|PubMed:12855696, ECO:0000269|PubMed:26731412, ECO:0000269|PubMed:8816748}. This is the function of Ensembl gene identifier ENSG00000131238 (PPT1, palmitoyl-protein thioesterase 1).