Frizzled 3, encoded by FZD3 gene, is a receptor in the Wnt/β-catenin pathway, a conserved signaling pathway that regulates gene expression and controls diverse developmental processes ¹. It belongs to the Frizzled protein family that contains multiple hydrophobic domains predicted to form seven transmembrane helices, similar to G protein coupled receptors. Conserved sequences are found in the Frizzled proteins extracellular cysteine-rich domain (CRD), the putative transmembrane domains, parts of the intracellular loops and a juxtamembrane motif, KTXXXW, found in the membrane-proximal C-terminal region of all Frizzleds. The C-terminal tails, however, are highly divergent ².  

Frizzled-3 is constitutively expressed in murine melanocyte precursors, melanocytes and human melanocytes ³, it is also expressed in the epidermis of the developing embryo ⁴ and its expression levels are changing between different parts of the ovary throughout the process of embryogenesis ¹. Because of its crucial role in regulating proper embryogenesis and its role in the development of the central nervous system, including synaptogenesis and structural plasticity, mutations in FZD3  gene were shown to have a significant association with the development of schizophrenia and other psychotic disorders ⁵.