521
The OTF interactions we observed extended over the heptamer element 5'-CTCAGGA-3' , and it seems likely that the binding of the purified factors involves cooperation between octamer and heptamer sites in this promoter .
 DNA: heptamer element; DNA: promoter; protein: purified factors
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 DNA: heptamer element; DNA: promoter; protein: purified factors