Subcellular localization of RPB5-mediating protein and its putative functional partner.
We previously identified a novel cellular protein, RPB5-mediating protein (RMP), that retains corepressor activity and functionally antagonizes transcriptional modulation via hepatitis B virus X protein. The subcellular localization of RMP was examined using green fluorescent protein-fused protein forms. We found that a nuclear localization signal (NLS) and a coiled-coil (CC) domain functioning as a cytoplasmic localization signal (CLS) are important for the subcellular localization of RMP. The CLS apparently acts dominantly, since RMP was mostly localized in the cytoplasm with weak and diffuse signals in the nucleus, and the NLS was indispensable for the nuclear localization of RMP only in the absence of the CLS. Using a yeast two-hybrid method, we isolated a putative corepressor, DNA methyltransferase 1-associating protein (DMAP1), which was found to bind to the CC domain of RMP. DMAP1 facilitated the nuclear localization of RMP and the corepressor activity of RMP in a dose-dependent manner by interacting with the CC domain of RMP. These results are discussed in light of a recent paper showing a novel evolutionarily conserved role of URI in the TOR signaling pathway.
Delgermaa
Luvsanjav
L
Department of Molecular Oncology, Cancer Research Institute, Kanazawa University, Takara-machi 13-1, Kanazawa 920-0934, Japan.
Hayashi
Naoyuki
N
Dorjsuren
Dorjbal
D
Nomura
Takahiro
T
Thuy
Le Thi-Thu
le TT
Murakami
Seishi
S
D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D017930:Genes, Reporter; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D018613:Microscopy, Confocal; D012097:Repressor Proteins / Q000378:metabolism*
D002352:Carrier Proteins; C411744:DMAP1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D012097:Repressor Proteins; C117184:URI1 protein, human