Diphtheria toxin receptor. Identification of specific diphtheria toxin-binding proteins on the surface of Vero and BS-C-1 cells.

摘要: The biochemical characteristics of specific receptor molecules for diphtheria toxin on the surface two toxin-sensitive cell lines (Vero and BS-C-1) were examined. Diphtheria was found to bind a number different proteins in Nonidet P-40 solubilized extracts 125I-labeled cells. In contrast, permitting first labeled intact cells, which subsequently subjected immunoprecipitation with anti-diphtheria toxin, resulted far more restricted profile toxin-binding that possessed Mrs range 10,000-20,000. Direct chemical cross-linking radioiodinated appearance several predominant bands possessing approximately 80,000. Mr 80,000 complexes shown be composed radiolabeled (Mr 60,000) unlabeled 20,000 cellular proteins. These judged result binding their could preferentially inhibited by addition 100-fold excess toxin. formation sensitive prior trypsin treatment cells known inhibitors binding. Furthermore, incubation at 37 degrees C ("down regulation") markedly specifically reduced subsequent cross-linked complexes, these down-regulated less cytotoxicity assays. Further restored ability form complexes; this regeneration requires protein synthesis restores cells' sensitivity toxin-mediated cytotoxicity. results strongly suggest 10,000-20,000 is, or constitutes portion of, functional receptor.