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Multiple mammalian proteasomal ATPases, but not proteasome itself, are associated with TATA‐binding protein and a novel transcriptional activator, TIP120
Author(s) -
Makino Yasutaka,
Yoshida Tatsushi,
Yogosawa Shingo,
Tanaka Keiji,
Muramatsu Masami,
Tamura Takaaki
Publication year - 1999
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.1999.00277.x
Subject(s) - biology , proteasome , proteolysis , tata binding protein , atpase , microbiology and biotechnology , aaa proteins , activator (genetics) , transcriptional regulation , transcription factor , biochemistry , dna binding protein , gene , enzyme
Background SUG1 belongs to proteasomal ATPase. Previous studies have demonstrated that SUG1 is associated with TBP. It is assumed to be involved in transcriptional regulation in addition to proteolysis. In this study, we investigated the association of mammalian SUG1 with TBP in more detail. Results Pull‐down experiments with TBP revealed multiple TBP‐interacting proteins (TIPs) that were recovered dependent upon the presence of C‐terminal conserved domain of TBP. By 2‐D electrophoresis, we identified SUG1 in TIPs. By using far‐Western analysis, we identified two proteins that could directly bind to TBP: SUG1 and another proteasomal ATPase (S4). Protein microsequencing and Western blotting identified all the remaining proteasomal ATPases (MSS1, TBP1, TBP7, and SUG2) in the TIP preparations. We present evidence that TBP and at least SUG1, MSS1, and S4 form a complex in the cell. However, no evidence of association of TBP with the 26S proteasome or its 19S regulatory unit was obtained. The molecular mass of the TBP/ATPases‐complex, which also included a novel transcription regulatory factor, TIP120, was estimated to be ≈800 kDa. Conclusion These results suggest that there is a novel multisubunit complex containing TBP and proteasomal ATPases. Based on our findings, we hypothesize that proteasomal ATPases are involved in transcriptional regulation in addition to proteolysis.