Carboxylesterase that acts as a key negative regulator of the Wnt signaling pathway by specifically mediating depalmitoleoylation of WNT proteins. Serine palmitoleoylation of WNT proteins is required for efficient binding to frizzled receptors (PubMed:25731175). . This is the function of NOTUM (notum, palmitoleoyl-protein carboxylesterase, Ensembl gene identifier ENSG00000185269).