Interaction between human topoisomerase I and a novel RING finger/arginine-serine protein.
The N-terminus of human topoisomerase I participates in the binding of this enzyme to helicases and other proteins. Using the N-terminal 250 amino acids of human topoisomerase I and a yeast two-hybrid/ in vitro binding screen, a novel arginine-serine-rich peptide was identified as a human topoisomerase I-binding protein. The corresponding full-length protein, named topors, contains a consensus RING zinc finger domain and nuclear localization signals in addition to the arginine-serine-rich region. The RING finger domain of topors is homologous to a similar domain in a family of viral proteins that are involved in the regulation of viral transcription. When expressed in HeLa cells as a green fluorescent protein fusion, topors localizes in the nucleus in a punctate pattern and co-immunoprecipitates with topoisomerase I. These data suggest that topors is involved in trans-cription, possibly recruiting topoisomerase I to RNA polymerase II transcriptional complexes.
Haluska
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P
Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, The Cancer Institute of New Jersey, University of Medicine and Dentistry of New Jersey, New Brunswick, NJ 08901, USA.
Saleem
A
A
Rasheed
Z
Z
Ahmed
F
F
Su
E W
EW
Liu
L F
LF
Rubin
E H
EH
D000595:Amino Acid Sequence; D002352:Carrier Proteins; D002467:Cell Nucleus / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D018076:DNA, Complementary / Q000032:analysis; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011233:Precipitin Tests; D012441:Saccharomyces cerevisiae; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors; D020298:U937 Cells; D044767:Ubiquitin-Protein Ligases; D016335:Zinc Fingers
D002352:Carrier Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; C120157:TOPORS protein, human; D044767:Ubiquitin-Protein Ligases; D004264:DNA Topoisomerases, Type I