Fig. 4.

Domain II, a potentially novelcis-regulatory element, interacts with nuclear protein(s) in a cell-specific manner. A, 22 bp oligonucleotide containing the domain II sequence formed a complex (CII) with nuclear extracts (20 μg) from BE(2)C or CATH.a cells but not from HeLa or C6 cells, indicating that domain II interacts with nuclear proteins in a cell-specific manner.B, CII is a sequence-specific complex. Twenty micrograms of SK-BE(2)C nuclear extracts were incubated with the radiolabeled domain II oligonucleotide. We used 40-fold (lanes 2,4, 6) or 400-fold (lanes 3, 5, 7) molar excesses of indicated cold oligonucleotides for competition. CII was competed by domain II cold oligonucleotide but not by its mutant form (II^m) or Sp1 sequence.