Interaction of thyroid-hormone receptor with a conserved transcriptional mediator

Abstract

The thyroid-hormone receptors are hormone-dependent transcription factors that control expression of many target genes. This regulation is presumably a consequence of hormone-dependent contacts between the receptors and the basal transcription machinery. We used the yeast two-hybrid system to identify a candidate human transcriptional mediator that interacts with both the thyroid-hormone receptor and the retinoid-X receptor in a ligand-dependent fashion. This protein, Trip1 (for thyroid-hormone-receptor interacting protein), shares striking sequence conservation with the yeast transcriptional mediator Sug1 (refs 6, 7). Here we show that Trip1 can functionally substitute for Sug1 in yeast, and that both proteins interact in vitro with the thyroid-hormone receptor, and with the transcriptional activation domains of yeast GAL4 and of herpes virus VP16.

Multiple mammalian proteasomal ATPases, but not proteasome itself, are associated with TATA‐binding protein and a novel transcriptional activator, TIP120

“…The results of genetic and transfection experiments have also indicated that some of these ATPases participate in transcriptional regulation. It has been suggested that yeast SUG1 acts as a mediator for a transcriptional activator in vivo (Swaffield et al 1992), and Trip1 (human SUG1) and mouse SUG1 were demonstrated to interact with various hormone receptors (Lee et al 1995;vom Baur et al 1996). Recently, mouse SUG1 was demonstrated to have a DNA helicase activity .…”

Characterization of the interaction between RhoA and the amino‐terminal region of PKN

“…50 nM of the guanine nucleotide bound form of RhoA fused to GST was incubated with 1.5 lal of in vitro translated PKN in a total volume of 200 Ixl of binding buffer (20 mM Tris/HC1 at pH 7.5, 1 mM EDTA, 0.5 mM DTr, 5 mM MgC12 and 1 I.tg/ml leupeptin) for 60 rain at 4°C. Then 40 ~tl of glutathione-Sepharose beads preincubated in binding buffer containing 10 mglml E. coli extracts to block non-specific binding [10], was added and rotated for 30 min at 4°C. Unbound proteins were removed by four washes with binding buffer containing 0.2% Nonidet P-40 and 50 mM NaC1, and by two washes with binding buffer.…”

Adenovirus early region 1A protein binds to mammalian SUG1-a regulatory component of the proteasome

“…These activities are mostly involved in the regulation of transcription in some way. For example, SUG1 (also called Trip1) can interact with nuclear hormone receptors and the basal transcriptional machinery (vom Baur et al, 1995;Lee et al, 1995), thus serving as a transcriptional mediator. It also possesses DNA helicase activity (Fraser et al, 1997) and binds directly to TBP .…”

“…It has recently been reported that the proteasomal regulatory component mouse SUG1 (mSUG1) which is of similar molecular weight will bind to the immediate early gene product c-Fos (Wang et al, 1996), TBP and nuclear receptors such as those for thyroid hormone (Lee et al, 1995). With this in mind, a possible interaction of Ad E1A with hSUG1 was investigated.…”

“…hSUG1 is a multifunctional protein which has been reported to be involved in many cellular processes beside proteasomal degradation (vom Baur et al, 1995;Lee et al, 1995;Fraser et al, 1997). With this in view, we compared its subcellular localization with that of the proteasomes using immuno¯uorescence analysis.…”