FGF-19

Human FGF19 cDNA predicts a 251 aa precursor protein with a 22 aa signal peptide and a 229 aa secreted mature protein with no potential N-linked glycosylation sites. Among FGF family members, human FGF19 is most closely related to chicken FGF19 and murine FGF15, sharing approximately 61% and 51% aa sequence identity, respectively. Neither the human orthologue of mouse FGF15, nor the mouse counterpart of human FGF19 has been identified. With the exception of adult gall bladder epithelium, FGF19 expression is restricted to fetal tissues. Unlike most FGFs which bind to and activate more than one FGF receptor, FGF19 is a specific ligand for FGF R4. Similarly, another FGF family member, FGF7 (KGF), only activates KGF R, the IIIb isoform of FGF R2. During chick embryogenesis, FGF19 has been shown to act synergistically with Wnt8c to initiate inner ear development.