Analysis of C.Esp1396I complexes with wild-type and mutant esp1396I promoters using electrophoretic mobility shift assay. (A) The sequences of the wild-type esp1396ICR C-boxes with symmetrical elements highlighted is presented at the top of the figure. Numbers below refer to positions of nucleotides in the C-box. The gels below show the results of native gel separation of complexes formed in the absence or in the presence of increasing concentrations of C.Esp1396I using wild-type esp1396ICR and various mutants. Note on nomenclature, every mutant fragment (‘mut’) is labeled to indicate positions of the boxes substituted (i.e. 1,2 in the second gel) and the bases introduced by the mutations (GT in the second gel). (B) As in (A), but using wild-type or mutant esp1396IM DNA fragments.