FIG. 1.

Effect of pH on DNA-binding activity of polyomavirus large T antigen. (A) Binding to nitrocellulose filters of 3 ng of ³²P-labeled 736-bp DNA fragment containing the wild-type polyomavirus origin region was carried out in 50 mM buffers of different pH values (pH 5.0 to 5.6, sodium acetate; pH 6.0 to 7.6, potassium phosphate; pH 8.0 to 8.5, Tris-HCl) after incubation in the presence (black bars) or absence (gray bars) of 100 ng of large T antigen (LT Ag). (B) The same DNA fragment was incubated with increasing amounts of large T antigen in potassium phosphate buffer at pH 6.0 (triangles) or pH 7.5 (squares). Radioactivity bound to filters in the absence of large T antigen was subtracted from the results to give corrected specific binding values.