Family with sequence similarity 20, member C also known as FAM20C or DMP4 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, respo ...
which in humans is encoded by the ''FAM20C''
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 ba ...
.
Fam20C, a Golgi localized protein kinase, is a serine kinase that phosphorylates both casein and other highly acidic proteins and members of the small integrin-binding ligand, the N-linked glycoproteins (SIBLING) family at the target motif SerXGlu.
Function
Dmp4 causes differentiation of
mesenchymal stem cell
Mesenchymal stem cells (MSCs) also known as mesenchymal stromal cells or medicinal signaling cells are multipotent stromal cells that can differentiate into a variety of cell types, including osteoblasts (bone cells), chondrocytes (cartilage c ...
s into functional
odontoblast
In vertebrates, an odontoblast is a cell of neural crest origin that is part of the outer surface of the dental pulp, and whose biological function is dentinogenesis, which is the formation of dentin, the substance beneath the tooth enamel on t ...
cells and is likely to function as a regulator of
dentin
Dentin () (American English) or dentine ( or ) (British English) ( la, substantia eburnea) is a calcified tissue of the body and, along with enamel, cementum, and pulp, is one of the four major components of teeth. It is usually covered by ena ...
mineralization.
FAM20C is a secretory kinase, responsible for the phosphorylation of all secreted proteins, from milk to bone proteins.
Phosphorylation by Fam20C in the secretory pathway is essential for proper biomineralization of bone. The substrate specificity of FAM20C indicates, however, that it is not likely to account for the tyrosine phosphorylation of the secreted protein. The characterization of FAM20C as an active serine kinase in the Golgi apparatus provides a clear precedent that ATP dependent protein phosphorylation can take place in the secretory apparatus.
Fam20C knockout mice develop severe hypophosphatemic rickets due to an increased renal phosphate wasting that is likely attributed to the remarkable elevation of serum fibroblast growth factor 23 (FGF23),
while their dentin and enamel defects are largely independent from the hypophosphatemia and appear to be a local effects of phosphorylation failure in the secretory calcium-binding phosphoproteins (SCPPs)
Clinical significance
Mutations in the FAM20C gene are associated with
Raine syndrome
Raine syndrome (RNS), also called osteosclerotic bone dysplasia, is a rare autosomal recessive congenital disorder
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. ...
.
References
Further reading
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