Figure 4.

Gel mobility shift assay using DNA fragments of EE-1 carrying consecutive 2- or 3-bp nucleotide substitutions. A, ³²P-labeled double-stranded oligonucleotide probes of EE-1 (lane 1) and modified probes carrying consecutive 2- or 3-bp nucleotide substitutions as shown in B (lanes 2–10) were incubated with 2.5 μg of nuclear proteins purified from cells grown under low-CO₂ conditions in light. F indicates the free probe. B, Nucleotide substitutions introduced into EE-1 are shown by lowercase letters. Nucleotide substitutions that abolished C-I complex formation are highlighted. A core sequence of EE-1 critical for interaction with the DNA-binding protein is boxed.