Protein-serine O-palmitoleoyltransferase that acts as a key regulator of the Wnt signaling pathway by mediating the attachment of palmitoleate, a 16-carbon monounsaturated fatty acid (C16:1), to Wnt proteins. Serine palmitoleylation of WNT proteins is required for efficient binding to frizzled receptors. (9Z)-hexadecenoyl-CoA + [Wnt protein]-L-serine = [Wnt protein]-O-(9Z)-hexadecenoyl-L-serine + CoA Interacts with WNT1, WNT3, WNT3A, WNT4, WNT5A, WNT5B, WNT6, WNT7A and WNT7B. Expressed in brain, heart, kidney, liver, lung, muscle, spleen and testis. Isoform 4 is strongly expressed in kidney, liver, lung, spleen and testis. Isoform 1 is strongly expressed in brain, heart and muscle and poorly in kidney, liver, lung, spleen and testis. Isoform 1, isoform 2, isoform 3 and isoform 4 are expressed at different levels in embryo at 9.5, 10.5, 11.5, 12.5, 13.5 and 15.5 dpc. Belongs to the membrane-bound acyltransferase family. Porcupine subfamily. Was initially thought to mediate palmitoylation of Wnt proteins. It was later shown that it instead acts as a serine O-palmitoleoyltransferase that mediates the attachment of palmitoleate, a 16-carbon monounsaturated fatty acid (C16:1), to Wnt proteins (PubMed:17141155, PubMed:24798332).