Frizzled-4 (Fz-4) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
that in humans is encoded by the ''FZD4''
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
.
Fz-4 has also been designated as CD344 (
cluster of differentiation
The cluster of differentiation (also known as cluster of designation or classification determinant and often abbreviated as CD) is a protocol used for the identification and investigation of cell surface molecules providing targets for immunophen ...
344).
Function
This gene is a member of the
frizzled
Frizzled is a family of atypical G protein-coupled receptors that serve as receptors in the Wnt signaling pathway and other signaling pathways. When activated, Frizzled leads to activation of Dishevelled in the cytosol.
Species distribution
Fr ...
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
Norrin, also known as Norrie disease protein or X-linked exudative vitreoretinopathy 2 protein (EVR2) is a protein that in humans is encoded by the ''NDP'' gene. Mutations in the NDP gene are associated with the Norrie disease.
Function
Signa ...
that is functionally similar but structurally different from Wingless type proteins.
FZD4 signaling induced by Norrin regulates vascular development of vertebrate
retina
The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...
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
A protein isoform, or "protein variant", is a member of a set of highly similar proteins that originate from a single gene or gene family and are the result of genetic differences. While many perform the same or similar biological roles, some iso ...
has been described, however, its expression is not supported by other experimental evidence.
See also
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Frizzled
Frizzled is a family of atypical G protein-coupled receptors that serve as receptors in the Wnt signaling pathway and other signaling pathways. When activated, Frizzled leads to activation of Dishevelled in the cytosol.
Species distribution
Fr ...
References
Further reading
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External links
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GeneReviews/NCBI/NIH/UW entry on Familial Exudative Vitreoretinopathy, Autosomal Dominant
{{G protein-coupled receptors, g4
Clusters of differentiation
G protein-coupled receptors