Receptor for Wnt proteins. Component of the Wnt-Fzd-LRP5-LRP6 complex that triggers beta-catenin signaling through inducing aggregation of receptor-ligand complexes into ribosome-sized signalsomes (By similarity). The beta-catenin canonical signaling pathway leads to the activation of disheveled proteins, inhibition of GSK-3 kinase, nuclear accumulation of beta-catenin and activation of Wnt target genes. A second signaling pathway involving PKC and calcium fluxes has been seen for some family members, but it is not yet clear if it represents a distinct pathway or if it can be integrated in the canonical pathway, as PKC seems to be required for Wnt-mediated inactivation of GSK-3 kinase. Both pathways seem to involve interactions with G-proteins. May be involved in transduction and intercellular transmission of polarity information during tissue morphogenesis and/or in differentiated tissues. Coreceptor along with RYK of Wnt proteins, such as WNT1. Component of a Wnt-signaling complex that contains a WNT protein, a FZD protein and LRP5 or LRP6. Interacts directly with LRP5 or LRP6; the interaction is promoted by Wnt-binding and signaling and inhibited by DKK1 (By similarity). Interacts (via the PDZ-binding motif) with GPOC (via its PDZ domain). Interacts with RSPO1 and RSPO3. Interacts with glypican GPC3 (By similarity). Colocalizes with GOPC at the Golgi apparatus. Expressed in chondrocytes. Lys-Thr-X-X-X-Trp motif interacts with the PDZ domain of Dvl (Disheveled) family members and is involved in the activation of the Wnt/beta-catenin signaling pathway. The FZ domain is involved in binding with Wnt ligands. Ubiquitinated by ZNRF3, leading to its degradation by the proteasome. Belongs to the G-protein coupled receptor Fz/Smo family.