FIG. 6.

Recognition of the proximal I-CCAAT box of the UXP promoter by a cellular factor. Nuclear extracts (NE) prepared from mock- or Ad5-infected A549 cells were used in an EMSA. Double-stranded DNA corresponding to the proximal I-CCAAT box of the UXP promoter was end labeled as the probe in the EMSA. In the competition reaction, the unlabeled wild-type double-stranded DNA containing an I-CCAAT box (Cold Oligo), a mutant I-CCAAT box (Cold Oligo Mut), or an unrelated DNA fragment (Cold Ap1) in a 50-fold molar excess was used in the reaction. The mutant I-CCAAT oligonucleotide carries the ATCAAAC mutation instead of the wild-type CCCCAAT sequence. Components in the binding reaction mixtures are shown at the top of the figure. Arrows at the left indicate the positions of DNA-protein complexes. The cold mutant I-CCAAT oligonucleotide was included in lanes d and h in panel B.