sentences:  Initiation of transcription requires promoter regions, which are specific nucleotide consensus sequences that tell the σ-factor on RNA polymerase where to bind to the DNA.The promoters are usually located 15 to 19 bases apart and are most commonly found upstream of the genes they control.RNA polymerase is made up of 4 subunits, which include two alphas, a beta, and a beta prime (α, α, β, and β').