Fig. 2. cAMP was titrated in the presence of 0.1 µM CRP using deoP2 DNA template. (A) The transcription products were resolved in denaturing 8% polyacrylamide gel (see Materials and methods). The rna1 and deoP2 RNAs were labeled as such. The cAMP concentration in each lane was as follows: 0, 0.1, 1, 10, 100 and 1000 µM for lanes 1–6. (B) deoP2 RNAs were quantified with a β-scanner (PhosphorImager; Molecular Dynamics, CA) and the total c.p.m. were plotted as a function of cAMP concentration.