Anthrax protective antigen interacts with a specific receptor on the surface of CHO-K1 cells.
The interaction of protective antigen (PA), a component of the anthrax toxin, with receptors on the Chinese hamster ovary cell line CHO-K1 was characterized. Protective antigen binding at 4 degrees C is highly specific, concentration dependent, saturable (Kd = 0.9 nM), and reversible. Scatchard analysis indicates the presence of a single class of PA binding sites at a concentration of 10,000 +/- 2,000 per cell. Pretreatment of cells with a number of different proteases strongly inhibits PA binding, suggesting that the receptor may be at least partially proteinaceous. Direct chemical cross-linking of radioiodinated PA to the cell surface results in the appearance of a major band exhibiting an apparent molecular mass of 170 kDa, as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The appearance of this band is completely inhibited by a 200-fold molar excess of unlabeled PA, indicating a high specificity for this interaction. Our results suggest that a cell surface protein(s) of 85 to 90 kDa is, or constitutes a portion of, a specific receptor for the PA.
Escuyer
V
V
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115.
Collier
R J
RJ
D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D001408:Bacillus anthracis / Q000276:immunology*; D001427:Bacterial Toxins / Q000276:immunology*; D002478:Cells, Cultured; D006224:Cricetinae; D006023:Glycoproteins / Q000032:analysis; D011971:Receptors, Immunologic / Q000032:analysis*
D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D006023:Glycoproteins; D011971:Receptors, Immunologic; C030325:anthrax toxin