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. Isoform 1 is expressed in fetal brain, brain, amygdala, caudate nucleus, cerebellum, hippocampus, pituitary, thalamus, heart, skeletal muscle and testis. Isoform 4 is expressed in amygdala, corpus callosum, hippocampus, spinal cord, kidney, liver, lung, spleen, uterus, testis. Isoform 2 and isoform 3 are expressed in substantia negra, spinal cord, heart and lung. The disease is caused by variants affecting the gene represented in this entry. Belongs to the membrane-bound acyltransferase family. Porcupine subfamily. Was initially thought to mediate palmitoylation of Wnt proteins (PubMed:24292069). 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. The sequence differs from that shown upstream of position 63 for unknown reasons. Porcupine homolog (Drosophila) (PORCN)