Description:
Canonical and non-canonical Wnt signaling pathways have in common Frizzled (Fz) as the core Wnt receptor element. Recent findings implicate that not only the choice of Wnt ligands, but also the presence of additional components in the receptor complex determine signaling pathway specificity. Vertebrate PTK7 (protein tyrosine kinase 7) encodes a catalytically inactive receptor-tyrosine kinase and is required for the control of planar cell polarity (PCP) in frogs and mice by acting as Fz co-receptor and inhibiting canonical Wnt signaling. Mutation of a Drosophila homolog of PTK7, the gene off...