Cryo-EM structure of human Wntless in complex with Wnt3a

Abstract Wntless (WLS), an evolutionarily conserved multi-pass transmembrane protein, is essential for secretion of Wnt proteins. Wnt-triggered signaling pathways control many crucial life events, whereas aberrant tightly associated with human diseases including cancers. Here, we report the cryo-EM structure WLS in complex Wnt3a, most widely studied Wnt, at 2.2 Å resolution. The domain bears a GPCR fold, core cavity and lateral opening. Wnt3a interacts multiple interfaces, lipid moiety on traversing hydrophobic tunnel inserting into membrane. A β-hairpin containing palmitoleoylation site extensively, which WLS-mediated secretion. flexibility loop/hairpin regions involved binding sites indicates induced fit might happen when Wnts are bound to different partners. Our findings provide important insights molecular mechanism palmitoleoylation, signaling.