Comparison of the CDP-ɛ site to upstream CDP-binding sites within the gp91^phox promoter. (A) EMSA was performed as described in Materials and Methods, with CDP-binding site probes and nuclear extract isolated from HeLa cells (10 μg for CDP-ɛ; 3 μg for the other 4 probes). Competition is with 10 ng of nonradioactive CDP-ɛ oligonucleotide or an equimolar amount of nonradioactive CDP-, CDP-β, CDP-γ, or CDP-δ oligonucleotides. Because of variations in probe specific activity and film exposure times, the absolute intensity of the CDP complex formed with each probe in the absence of competitor does not reflect the relative affinity of CDP for each binding site. (B) Alignment of 5 CDP-binding sites within the gp91^phox promoter against a PCR-selected consensus CDP-binding sequence.18 The lowercase nucleotides do not match the consensus sequence. The percent similarity between each gp91^phox promoter site and the PCR selected consensus sequence is indicated.