Ligand for members of the frizzled family of seven transmembrane receptors (PubMed:17117926). Can activate or inhibit canonical Wnt signaling, depending on receptor context (PubMed:16602827). In the presence of FZD4, activates beta-catenin signaling. In the presence of ROR2, inhibits the canonical Wnt pathway by promoting beta-catenin degradation through a GSK3-independent pathway which involves down-regulation of beta-catenin-induced reporter gene expression (PubMed:16602827). Suppression of the canonical pathway allows chondrogenesis to occur and inhibits tumor formation. Stimulates cell migration (PubMed:17117926). Decreases proliferation, migration, invasiveness and clonogenicity of carcinoma cells and may act as a tumor suppressor. Mediates motility of melanoma cells (By similarity). Required during embryogenesis for extension of the primary anterior-posterior axis and for outgrowth of limbs and the genital tubercle (PubMed:10021340). Inhibits type II collagen expression in chondrocytes (By similarity). Forms a soluble 1:1 complex with AFM; this prevents oligomerization and is required for prolonged biological activity. The complex with AFM may represent the physiological form in body fluids (By similarity). Homooligomer; disulfide-linked, leading to inactivation (PubMed:22726442). Interacts with PORCN (PubMed:10866835). Interacts with WLS (PubMed:19841259). Interacts with glypican GCP3 (By similarity). Interacts with PKD1 (via extracellular domain) (PubMed:27214281). Expressed in a gradient at the caudal end of the embryo during gastrulation and later in the distal-most aspect of several structures that extend from the body such as the limbs and genital tubercle. Glycosylation is necessary for secretion but not for activity. Palmitoleoylation is required for efficient binding to frizzled receptors. Depalmitoleoylation leads to Wnt signaling pathway inhibition. Proteolytic processing by TIKI1 and TIKI2 promotes oxidation and formation of large disulfide-bond oligomers, leading to inactivation of WNT5A. Mice display perinatal lethality and display gross morphological defects in outgrowing tissues. They are truncated caudally, displaying loss of the tail and a significant shortening of the anterior-posterior axis. The shape of the head is abnormal with truncated snout, mandible and tongue and reduced outgrowth of the external ear. Fore- and hindlimbs lack digits, the genital tubercle is missing and chondrocyte differentiation is inhibited. Belongs to the Wnt family. A palmitoylation site was proposed at Cys-104, but it was later shown that this cysteine is engaged in a disulfide bond.