Description
It is a single-pass transmembrane protein composed of three extracellular Ig-like domains, a transmembrane region, and a tyrosine kinase domain (1, 2). Tyrosine-protein kinase that acts as cell-surface receptor for fibroblast growth factors and plays an essential role in the regulation of cell proliferation, differentiation and apoptosis (3, 4, 5, 6). Plays an essentialrole in the regulation of chondrocyte differentiation, proliferation and apoptosis, and is required for normal skeleton development. Regulates both osteogenesis and postnatal bone mineralization by osteoblasts. Promotes apoptosis in chondrocytes, but can also promote cancer cell proliferation. Required for normal development of the inner ear. Phosphorylates PLCG1, CBL and FRS2. Ligand binding leads to the activation of several signalling cascades(6). Activation of PLCG1 leads to the production of the cellular signalling moleculesdiacylglycerol and inositol 1,4,5-trisphosphate. Phosphorylation of FRS2 triggersrecruitment of GRB2, GAB1, PIK3R1 and SOS1, and mediates activation of RAS,MAPK1/ERK2, MAPK3/ERK1 and the MAP kinase signalling pathway, as well as of the AKT1signalling pathway (7, 8, 9). Plays a role in the regulation of vitamin D metabolism.Mutations that lead to constitutive kinase activation or impair normal FGFR3 maturation,internalization and degradation lead to aberrant signalling (10, 11). Over-expressed orconstitutively activated FGFR3 promotes activation of PTPN11/SHP2, STAT1, STAT5A andSTAT5B. Secreted isoform 3 retains its capacity to bind FGF1 and FGF2 and hence mayinterfere with FGF signalling.
FGFR3b is an alternatively spliced isoform representing epithelial variant of FGFR3