Figure 5.

TRBP associates with DRIP130 and p300. (A) TRBP C terminus interacts with endogenous DRIP130 from GH₃ nuclear extract. GST-TRBP fusion proteins were incubated with GH₃ nuclear extract, and TRBP-bound proteins were subjected to Western blot analysis. Arrow indicates DRIP130 detected by anti-DRIP130. Input was 5%. (B) 293 cells were transfected with (+) or without (−) indicated Flag-p300-(1661–2414) (5) or Flag-TRBP-(1–719) as control. Nuclear extracts from transfected cells were incubated with GST or GST-TRBP. Washed GST beads were subjected to Western blot analysis. Arrow indicates TRBP-bound p300 detected by anti-Flag antibody. Input was 10%. (C) In vitro translated, ³⁵S-labeled p300 fragments were tested for binding to GST and GST-TRBP-(1641-2063). Bound p300 was detected by SDS/PAGE and autoradiography. Input was 20%.