Ligand for members of the frizzled family of seven transmembrane receptors. Plays an important role in embryonic kidney development. Acts downstream of Notch signaling during pronephric kidney development. During early pronephros development, patterns the proximal pronephric anlagen to promote glomus and nephrostome formation. Also required later in pronephros development for tubulogenesis. Expressed in the brain and floor plate. In the developing pronephros, expressed in the proximal tubules and nephrostomes but absent from the pronephric duct. Expression during the neurula through tadpole stages of development. By Notch signaling in the pronephros. Palmitoleoylation is required for efficient binding to frizzled receptors. Depalmitoleoylation leads to Wnt signaling pathway inhibition. Belongs to the Wnt family.