Carboxylesterase that acts as a key negative regulator of the Wnt signaling pathway (PubMed:21566195). Acts by specifically mediating depalmitoleoylation of WNT proteins. Serine palmitoleoylation of WNT proteins is required for efficient binding to frizzled receptors (By similarity). Promotes head regeneration following amputation by inhibiting the Wnt signaling pathway. [Wnt protein]-O-(9Z)-hexadecenoyl-L-serine + H2O = (9Z)-hexadecenoate + [Wnt protein]-L-serine + H(+) Expressed in the anterior pole. Strongly up-regulated near anterior-facing wounds following head and tail amputation. Belongs to the pectinacetylesterase family. Notum subfamily.