Figure 6. G-1 binds to the colchicine binding site in β-tubulin.

The ability of G-1 to bind to the colchicine binding site in tubulin was evaluated with a colchicine site competitive assay. Incubation with colchicine, G-1, fluorescein-labelled G-1 and 2-ME suppressed H³-Colchicine binding in a concentration dependent manner. Incubation with vinblastine, which was used as a negative control, had no effect on H³-Colchicine binding to β-tubulin. Each point represents mean ± SEM (n = 4). The competition analysis was repeated for three times. FG-1: fluorescein-labelled G-1. 2-ME; 2-methoxyestradiol.