Tight folding of acidic fibroblast growth factor prevents its translocation to the cytosol with diphtheria toxin as vector.
A fusion protein of acidic fibroblast growth factor and diphtheria toxin A-fragment was disulfide-linked to the toxin B-fragment. The complex bound specifically to diphtheria toxin receptors, and subsequent exposure to low pH induced the fusion protein to translocate to the cytosol. Heparin, inositol hexaphosphate and inorganic sulfate strongly increased the trypsin resistance of the growth factor part of the fusion protein, indicating tight folding, and they prevented translocation of the fusion protein to the cytosol. The data indicate that only a more disordered form of the growth factor is translocation competent.
D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism*; D004277:DNA, Single-Stranded; D004167:Diphtheria Toxin / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D016220:Fibroblast Growth Factor 1 / Q000737:chemistry* / Q000378:metabolism; D006493:Heparin / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D010833:Phytic Acid / Q000494:pharmacology; D010957:Plasmids; D017510:Protein Folding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013431:Sulfates / Q000494:pharmacology; D014709:Vero Cells
D004277:DNA, Single-Stranded; D004167:Diphtheria Toxin; D011993:Recombinant Fusion Proteins; D013431:Sulfates; D016220:Fibroblast Growth Factor 1; D010833:Phytic Acid; D006493:Heparin