Receptor for Wnt proteins (By similarity). Most frizzled receptors are coupled to the beta-catenin canonical signaling pathway, which leads to the activation of disheveled proteins, inhibition of GSK-3 kinase, nuclear accumulation of beta-catenin and activation of Wnt target genes (By similarity). 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 (By similarity). Both pathways seem to involve interactions with G-proteins (By similarity). May be involved in transduction and intercellular transmission of polarity information during tissue morphogenesis and/or in differentiated tissues (By similarity). Interacts (via FZ domain) with TSKU; TSKU competes with WNT2B for binding to FZD4, inhibiting Wnt signaling and repressing peripheral eye development. Expressed in the developing kidney, interdigital spaces and optic cup. Expressed in optic cup at stages 10-19 and in nephric tubules from stage 10 to 20 and more. Expression in interdigital space begins at stage 20. 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. Belongs to the G-protein coupled receptor Fz/Smo family.