FIG. 1.

DNA binding activities of E2 DBD point mutant proteins. Levels of mutant E2 DBDs were determined by Western blot analysis using a polyclonal antibody to E2 and quantitated by using an IS 1000 Digital Imaging system. Three different dilutions of crude E. coli extracts containing the wt E2 DBD (lanes 1 to 3, bottom panel) were used as standards for levels of expression of five different mutant proteins (lanes 4 to 8, bottom panel), and equivalent amounts of protein were used to test for DNA binding activity by EMSA. Twofold titrations of the wt protein (lanes 1 to 5, top panel) or mutant proteins (lanes 6 to 30, top panel) were analyzed on a 5% polyacrylamide gel. Lane 31 contained probe alone.