FIG. 5.

DN-CBP inhibits the transcriptional synergy between CIITA and CBP. pDRASCAT was coexpressed with CIITA individually and in combination with CBP in 293T cells. In addition, DN-CBP, which contains amino acids from positions 1903 to 2441 in CBP, was coexpressed in these cells. Amounts of cotransfected plasmids were kept constant (0.5 μg of pDRASCAT and pCRDN-DBP; 0.25 μg of pCMVCBP and pSVCIITA; empty plasmid vector was included to maintain the total amount of transfected plasmid at 2.0 μg). pDRASCAT was coexpressed with empty plasmid vector (white bar), CIITA (gray bar), CIITA and CBP (black bar), CIITA, CBP, and DN-CIITA (cross-hatched bar), CIITA and DN-CBP (small-squares bar), or DN-CBP (striped bar). Fold transactivation (TA) was calculated from the bar graph and represents values of top bars over the value obtained with pDRASCAT alone. CAT activities represent mean values of three different experiments performed in triplicate with indicated standard errors of the mean.