title: Fibroblast growth factor homologous factor 1B binds to the C terminus of the tetrodotoxin-resistant sodium channel rNav1.9a (NaN).
abstract: In this study we demonstrate a direct interaction between a cytosolic fibroblast growth factor family member and a sodium channel. A yeast two-hybrid screen for proteins that associate with the cytoplasmic domains of the tetrodotoxin-resistant sodium channel rNa(v)1.9a (NaN) led to the identification of fibroblast growth factor homologous factor 1B (FHF1B), a member of the fibroblast growth factor family, as an interacting partner of rNa(v)1.9a. FHF1B selectively interacts with the C-terminal region but not the other four intracellular segments of rNa(v)1.9a. FHF1B binds directly to the C-terminal polypeptide of rNa(v)1.9a both in vitro and in mammalian cell lines. The N-terminal 5-77 amino acid residues of FHF1B are essential for binding to rNa(v)1.9a. FHF1B did not interact with C termini of two other sodium channels hNa(v)1.7a (hNaNE) and rNa(v)1.8a (SNS), which share 50% similarity to the C-terminal polypeptide of rNa(v)1.9a. FHF1B is the first growth factor found to bind specifically to a sodium channel. Although the functional significance of this interaction is not clear, FHF1B may affect the rNa(v)1.9a channel directly or by recruiting other proteins to the channel complex. Alternatively, it is possible that rNa(v)1.9a may help deliver this factor to the cell membrane, where it exerts its function.
authors.affiliation: Department of Neurology and Paralyzed Veterans of America/Eastern Paralyzed Veterans Association Neuroscience Research Center, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
authors.lastname: Liu Cj
authors.forename: S D
authors.initials: SD
authors.lastname: Dib-Hajj
authors.forename: S G
authors.initials: SG
authors.lastname: Waxman
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D017124:Conserved Sequence; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004351:Drug Resistance; D005346:Fibroblast Growth Factors; D015723:Gene Library; D005982:Glutathione Transferase / Q000378:metabolism; D006133:Growth Substances / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D062558:NAV1.9 Voltage-Gated Sodium Channel; D009479:Neuropeptides / Q000737:chemistry* / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015222:Sodium Channels / Q000737:chemistry* / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology*; D014018:Tissue Distribution; D020798:Two-Hybrid System Techniques
chemical_list: D018076:DNA, Complementary; C486356:FGF12 protein, human; C108110:Fgf12 protein, mouse; D006133:Growth Substances; D062558:NAV1.9 Voltage-Gated Sodium Channel; D009479:Neuropeptides; C491886:SCN11A protein, human; C491885:Scn11a protein, mouse; C113705:Scn11a protein, rat; D015222:Sodium Channels; D013779:Tetrodotoxin; D005346:Fibroblast Growth Factors; D012313:RNA; D005982:Glutathione Transferase