Fig. 7. Isopentenyl adenine binding to whole cells. (A) Cells of strain AX4 were developed on filters for 22 hours, dissociated, washed and suspended at 2.5x10⁷/ml in binding buffer containing 1.25 mM adenine. ³H-isopentenyl adenine was added to the indicated concentrations and the amount of specific binding determined after 5 minutes at 20°C. (B) Vegetative and 22 hour developed AX4, acrA^- and dhkB^- cells were suspended at 2.5x10⁷/ml in binding buffer containing 1.25 mM adenine. ³H-isopentenyl adenine (10 nM) was added and the amount of specific binding determined after 5 minutes at 20°C. All experiments were repeated at least three times.