The function of the octamer-binding site in the DRA promoter

The octamer binding site, which is located immediately upstream of the poorly conserved DRA TATA sequence, is important fof high levels of expression of this human major histocompatibility class II gene in B cells. In this study, we demonstrate that the substitution of the DRA TATA sequence with the TATA box from the adenovirus E1b promoter revomes the requirements for the octamer binding site for high levels of expression from DRA promoter. Since only the TATA box from the E1b but bot the DRA promoters binds the TATA binding protein, we conclude that the octamer binding site helps to recruit TBP to the DRA promoter.