Identification and characterization of a novel, intracellular isoform of fibroblast growth factor receptor-1(FGFR-1).
A novel, low molecular weight, intracellular isoform of FGF receptor-1 (FGFR-1) was identified in embryonic chicken tissues using several antibodies specific for different domains of FGF receptors. This low molecular weight isoform differs from the previously characterized isoforms of FGFR-1 in that it contains little or no carbohydrate. Furthermore, in contrast to the other isoforms of FGFR-1, this novel isoform is located exclusively intracellularly. However, it is capable of binding 125I-FGF-2 and it possesses intrinsic kinase activity. Pulse-chase experiments indicate that this isoform of FGFR-1 is not simply a precursor to glycosylated FGFR-1 since it can be detected long after the appearance of glycosylated FGFR-1 in the cells. These results suggest that the novel FGFR-1 isoform plays a role in regulating FGF activity distinct from cell surface, glycosylated FGFR-1. The possible roles of this FGFR-1 variant in FGF signaling are discussed.
Department of Cell Biology, Scripps Research Institute, La Jolla, California 92037, USA.
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Maher
D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000378:metabolism; D015152:Blotting, Northern; D002478:Cells, Cultured; D002642:Chick Embryo; D004591:Electrophoresis, Polyacrylamide Gel; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D006031:Glycosylation; D015151:Immunoblotting; D008970:Molecular Weight; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D011485:Protein Binding; D017468:Receptors, Fibroblast Growth Factor / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism
D000906:Antibodies; D017468:Receptors, Fibroblast Growth Factor; D016222:Fibroblast Growth Factor 2