TFB is recruited by another translation factor, TBP, after it recognizes the TATA box and bends the DNA so transcription can initiate. TFB stabilizes the TBP-DNA complex so that the proteins can recruit RNA Polymerase and melt the DNA via a yet-unknown mechanism. This opening of the DNA is not an energy-dependent process in Archaea; since TFB, TBP, and RNAP are located more closely to each other than in Eukarya, the tightness of the proteins and their interactions may provide more areas of contact to open the DNA as well as physically strain the DNA, which leads to an open transcription complex.
TFB uses a zinc ion (Zn) as a cofactor and accepts one ion per subunit.