Frizzled-7

The Wnt genes encode a large family of glycoproteins that are essential in development and tissue maintenance. Members of the Frizzled family of proteins serve as receptors for the Wnt signaling pathway. The predicted structure of Frizzled proteins is similar among all family members, containing a divergent N-terminal signal peptide, a highly conserved extracellular cysteine-rich domain (CRD), a variable length linker region, a seven-pass transmembrane region, and a variablelength C-terminal cytoplasmic domain. The CRD, which comprises the Wnt binding site, spans about 130 amino acid residues and contains ten invariant cysteine residues. Mouse Frizzled-7 contains 572 amino acid residues and shares 99% identity with the human orthologue in the CRD. Frizzled7 mRNA has been detected in relatively large amounts in adult skeletal muscle, plancenta and heart, and fetal kidney and lung. Several Frizzled-dependent signaling pathways exist. Their activation depends on the Wnt ligand and the cell context. Frizzled-7 can activate canonical Wnt/βCatenin signaling, as well as a noncanonical pathway involved in tissue morphogenesis.