Ligand for members of the frizzled family of seven transmembrane receptors. Required in embryonic development for endoderm specification and the correct positioning and orientation of the mitotic spindles and division planes in blastomere cells (PubMed:9288750, PubMed:9288749, PubMed:16678095, PubMed:25344071). Involved in cleavage axis determination (PubMed:9288750). Binds to receptor tyrosine kinase cam-1 (PubMed:17942487). Together with wnt ligand lin-44, plays a role in controlling vulva precursor cell P7.p lineage orientation during vulva development, probably by acting as a ligand for tyrosine kinase receptor lin-18 (PubMed:15369677). May act redundantly with other Wnt ligands such as cwn-1 and cwn-2 to control seam cell polarity (PubMed:22022276). Expressed by anchor cell and vulva precursor cell descendants P5.ppa, P5.ppp, P7.paa and P7.pap (PubMed:15369677). Expressed in the tail and weakly expressed in the vulva and body wall muscles (PubMed:20711352). Palmitoleoylation is required for efficient binding to frizzled receptors. Depalmitoleoylation leads to Wnt signaling pathway inhibition. Embryonic lethal with severely defective embryonic morphogenesis with the formation of unspecified differentiated tissues, no endoderm and excess mesoderm (PubMed:9288749). In addition, embryos have defective mitotic spindle orientation in the 8-cell stage ABar blastomere (PubMed:9288749, PubMed:16678095). RNAi-mediated knockdown results in irregular distribution of the mitotic spindle orientating factor sdn-1 and wnt signaling protein mig-5, with premature accumulation of sdn-1 on the cell surface of the ABar blastomere during the prophase stage of mitosis, and reduced accumulation of mig-5 at cell contact sites between the Abar and C blastomere cells, respectively (PubMed:25344071). Belongs to the Wnt family.