Fig. 2.

Protein factors bind independently to domains I, II, III, and IV. Nuclear extracts from SK-N-BE(2)C, CATH.a, HeLa, and C6 cells were used for DNase I footprinting analyses of the wild-type and mutant upstream promoters of the human DBH gene. The coding strand probes were prepared using wild-type (lane 1), domain I^m (lane 2), domain II^m (lane 3), and domain III^m (lane 4) mutant constructs. Each ³²P-labeled probe was digested with DNase I in the presence of each nuclear extract. The TATA box and four footprinted domains are denoted by brackets at the right side of the panel. The patterns of DNA–protein interaction at these domains appear to be conserved among DBH-expressing cell lines [SK-N-BE(2)C and CATH.a] and significantly differed from those of nonexpressing (HeLa and C6) cell lines.