Fig. 6. cAMP and cGMP binding to the lysates of mutant cells. (A) Binding of 50 nM [³H]cGMP or [³H]cAMP to the cytosolic fraction of a cell lysate was measured. The results are expressed as the amount of cyclic nucleotide bound per mg protein. The black bar represent lysates of gbpC^–/gbpD^– cells, the grey bar, gbpC^–/gbpD^–/N-GbpD-GFP^OE cells and the white bar, lysates of gbpC^–/gbpD^–/GbpD^OE cells. (B) Binding of 5 nM [³H]cGMP to the cytosolic fraction of lysates of gbpC^– cells (black bar) and gbpC^–/N-GbpC-GFP^OE cells (grey bar) was measured. The means±s.d. of at least two independent experiments with quadruple determinations are shown.