Eubacterial rNa polymerase have four types of subunit a, B, and B have rather constant sizes in different bacterial species, but o varies more widely Gene product Functions enzyme assembly rpoA 2 a subunits promoter recognition (40 KD each) binds some activators rpoB阝 subunit (155kD) roc阝 subunit catalytic center (160kD) rpoD o subunit (3290kD) promoter specificity 入入 E. coli enzyme 465kDEubacterial RNA polymerase have four types of subunit; α,β,and β’ have rather constant sizes in different bacterial species,but σ varies more widely