Frizzled-4(Fz-4) is a protein that in humans is encoded by the FZD4 gene. [5] [6] [7] Fz-4 has also been designated as CD344 (cluster of differentiation 344).
This gene is a member of the frizzled gene family. Members of this family encode seven-transmembrane domain proteins that are receptors for the Wingless type MMTV integration site family of signaling proteins. Frizzled-4 is the only representative of frizzled family members that binds strongly an additional ligand Norrin that is functionally similar but structurally different from Wingless type proteins. [8] FZD4 signaling induced by Norrin regulates vascular development of vertebrate retina and controls important blood vessels in the ear. Most frizzled receptors are coupled to the beta-catenin canonical signaling pathway. This protein may play a role as a positive regulator of the Wingless type MMTV integration site signaling pathway. A transcript variant retaining intronic sequence and encoding a shorter isoform has been described, however, its expression is not supported by other experimental evidence. [7]
This article incorporates text from the United States National Library of Medicine, which is in the public domain.