Gene Summary: The protein encoded by this gene is a member of the fibroblast growth factor receptor family, where amino acid sequence is highly conserved between members and throughout evolution. FGFR family members differ from one another in their ligand affinities and tissue distribution. A full-length representative protein consists of an extracellular region, composed of three immunoglobulin-like domains, a single hydrophobic membrane-spanning segment and a cytoplasmic tyrosine kinase domain. The extracellular portion of the protein interacts with fibroblast growth factors, setting in motion a cascade of downstream signals, ultimately influencing mitogenesis and differentiation. This particular family member is a high-affinity receptor for acidic, basic and/or keratinocyte growth factor, depending on the isoform. Mutations in this gene are associated with Crouzon syndrome, Pfeiffer syndrome, Craniosynostosis, Apert syndrome, Jackson-Weiss syndrome, Beare-Stevenson cutis gyrata syndrome, Saethre-Chotzen syndrome, and syndromic craniosynostosis. Multiple alternatively spliced transcript variants encoding different isoforms have been noted for this gene. General information above from NCBI
Catalytic activity: ATP + a [protein]-L-tyrosine = ADP + a [protein]-L-tyrosine phosphate.
Enzyme regulation: Present in an inactive conformation in the absence of bound ligand. Ligand binding leads to dimerization and activation by autophosphorylation on tyrosine residues. Inhibited by ARQ 523 and ARQ 069; these compounds maintain the kinase in an inactive conformation and inhibit autophosphorylation.
Subunit structure: Monomer. Homodimer after ligand binding. Interacts predominantly with FGF1 and FGF2, but can also interact with FGF3, FGF4, FGF6, FGF7, FGF8, FGF9, FGF10, FGF17, FGF18 and FGF22 (in vitro). Ligand specificity is determined by tissue-specific expression of isoforms, and differences in the third Ig-like domain are crucial for ligand specificity. Isoform 1 has high affinity for FGF1 and FGF2, but low affinity for FGF7. Isoform 3 has high affinity for FGF1 and FGF7, and has much higher affinity for FGF7 than isoform 1 (in vitro). Affinity for fibroblast growth factors (FGFs) is increased by heparan sulfate glycosaminoglycans that function as coreceptors. Likewise, KLB increases the affinity for FGF19 and FGF21. Interacts with PLCG1, GRB2 and PAK4.
Domain: The second and third Ig-like domains directly interact with fibroblast growth factors (FGF) and heparan sulfate proteoglycans. Alternative splicing events affecting the third Ig- like domain are crucial for ligand selectivity.
Subcellular location: Cell membrane; Single-pass type I membrane protein. Golgi apparatus. Cytoplasmic vesicle. Note=Detected on osteoblast plasma membrane lipid rafts. After ligand binding, the activated receptor is rapidly internalized and degraded.
Isoform 1: Cell membrane; Single-pass type I membrane protein. Note=After ligand binding, the activated receptor is rapidly internalized and degraded.
Isoform 3: Cell membrane; Single-pass type I membrane protein. Note=After ligand binding, the activated receptor is rapidly internalized and degraded.
Isoform 14: Secreted.
Isoform 19: Secreted.
Post-translational: Autophosphorylated. Binding of FGF family members together with heparan sulfate proteoglycan or heparin promotes receptor dimerization and autophosphorylation on several tyrosine residues. Autophosphorylation occurs in trans between the two FGFR molecules present in the dimer. Phosphorylation at Tyr-769 is essential for interaction with PLCG1.
N-glycosylated in the endoplasmic reticulum. The N-glycan chains undergo further maturation to an Endo H-resistant form in the Golgi apparatus.
Ubiquitinated. FGFR2 is rapidly ubiquitinated after autophosphorylation, leading to internalization and degradation. Subject to degradation both in lysosomes and by the proteasome.
Involvement in disease: Crouzon syndrome (CS) [MIM:123500]: An autosomal dominant syndrome characterized by craniosynostosis, hypertelorism, exophthalmos and external strabismus, parrot-beaked nose, short upper lip, hypoplastic maxilla, and a relative mandibular prognathism. Note=The disease is caused by mutations affecting the gene represented in this entry.
Jackson-Weiss syndrome (JWS) [MIM:123150]: An autosomal dominant craniosynostosis syndrome characterized by craniofacial abnormalities and abnormality of the feet: broad great toes with medial deviation and tarsal-metatarsal coalescence. Note=The disease is caused by mutations affecting the gene represented in this entry.
Apert syndrome (APRS) [MIM:101200]: A syndrome characterized by facio-cranio-synostosis, osseous and membranous syndactyly of the four extremities, and midface hypoplasia. The craniosynostosis is bicoronal and results in acrocephaly of brachysphenocephalic type. Syndactyly of the fingers and toes may be total (mitten hands and sock feet) or partial affecting the second, third, and fourth digits. Intellectual deficit is frequent and often severe, usually being associated with cerebral malformations. Note=The disease is caused by mutations affecting the gene represented in this entry.
Pfeiffer syndrome (PS) [MIM:101600]: A syndrome characterized by the association of craniosynostosis, broad and deviated thumbs and big toes, and partial syndactyly of the fingers and toes. Three subtypes are known: mild autosomal dominant form (type 1); cloverleaf skull, elbow ankylosis, early death, sporadic (type 2); craniosynostosis, early demise, sporadic (type 3). Note=The disease is caused by mutations affecting the gene represented in this entry.
Beare-Stevenson cutis gyrata syndrome (BSTVS) [MIM:123790]: An autosomal dominant disease characterized by craniofacial anomalies, particularly craniosynostosis, and ear defects, cutis gyrata, acanthosis nigricans, anogenital anomalies, skin tags, and prominent umbilical stump. The skin furrows have a corrugated appearance and are widespread. Cutis gyrata variably affects the scalp, forehead, face, preauricular area, neck, trunk, hands, and feet. Note=The disease is caused by mutations affecting the gene represented in this entry.
Familial scaphocephaly syndrome (FSPC) [MIM:609579]: An autosomal dominant craniosynostosis syndrome characterized by scaphocephaly, macrocephaly, hypertelorism, maxillary retrusion, and mild intellectual disability. Scaphocephaly is the most common of the craniosynostosis conditions and is characterized by a long, narrow head. It is due to premature fusion of the sagittal suture or from external deformation. Note=The disease is caused by mutations affecting the gene represented in this entry.
Lacrimo-auriculo-dento-digital syndrome (LADDS) [MIM:149730]: An autosomal dominant ectodermal dysplasia, a heterogeneous group of disorders due to abnormal development of two or more ectodermal structures. Lacrimo-auriculo-dento-digital syndrome is characterized by aplastic/hypoplastic lacrimal and salivary glands and ducts, cup-shaped ears, hearing loss, hypodontia and enamel hypoplasia, and distal limb segments anomalies. In addition to these cardinal features, facial dysmorphism, malformations of the kidney and respiratory system and abnormal genitalia have been reported. Craniosynostosis and severe syndactyly are not observed. Note=The disease is caused by mutations affecting the gene represented in this entry.
Antley-Bixler syndrome, without genital anomalies or disordered steroidogenesis (ABS2) [MIM:207410]: A rare syndrome characterized by craniosynostosis, radiohumeral synostosis present from the perinatal period, midface hypoplasia, choanal stenosis or atresia, femoral bowing and multiple joint contractures. Arachnodactyly and/or camptodactyly have also been reported. Note=The disease is caused by mutations affecting the gene represented in this entry.
Bent bone dysplasia syndrome (BBDS) [MIM:614592]: A perinatal lethal skeletal dysplasia characterized by poor mineralization of the calvarium, craniosynostosis, dysmorphic facial features, prenatal teeth, hypoplastic pubis and clavicles, osteopenia, and bent long bones. Dysmorphic facial features included low-set ears, hypertelorism, midface hypoplasia, prematurely erupted fetal teeth, and micrognathia. Note=The disease is caused by mutations affecting the gene represented in this entry.
Sequence similarities: Belongs to the protein kinase superfamily. Tyr protein kinase family. Fibroblast growth factor receptor subfamily.
Contains 3 Ig-like C2-type (immunoglobulin-like) domains.
Contains 1 protein kinase domain.
General information above from UniProt