Figure 4. The effect of the two CBP-interacting sites on CBP putative transactivation activity in HeLa cells.

(a) HeLa cells were transiently transfected with 0.25 μg of pM.CBP_2041-2240 and 0.25 μg of pSG5.HA or various pSG5.HA.GRIP1 fragments, along with the GK1 reporter gene (0.5 μg). LUC activities of the transfected cell extracts were determined. The basal activity of pM.CBP_2041-2240 is indicated by the dotted line. The two sub-CBP-interaction domains are labelled I and II. (b) COS-7 cells were transiently transfected in six-well plates with 1 μg of the indicated pSG5.HA.GRIP1 fragments. Immunoblots were performed as described in the Materials and methods section using 30% of the extract from lysates for immunoprecipitation and monoclonal antibody 3F10 (Roche) against the HA tag. These data (a) are the average of three experiments (means±S.D.; n=3).