Identifying control sequences by deletion analysis

5' deletion analysis is a method where upstream base pairs are systematically cut. for example -20 to +1 then the second would be -15 to +1 third -10 to +1 and so on. these segments are then bound with a reporter gene and transfected into E. coli cells. The E.coli cells are used to translate and transcribe the reporter genes. prepare the cell extracts and measure the reporter gene expression.