title: PCIF1, a novel human WW domain-containing protein, interacts with the phosphorylated RNA polymerase II.
abstract: Phosphorylation of the carboxy-terminal domain (CTD) of RNA polymerase II (RNAP II) largest subunit has an important role in transcription elongation and in coupling transcription to pre-mRNA processing. To identify proteins that can directly bind to the phosphorylated CTD, we screened a human cDNA expression library using 32P-labeled CTD as a probe. Here we report the cloning and characterization of a novel human WW domain-containing protein, PCIF1 (phosphorylated CTD interacting factor 1). PCIF1 is composed of 704 amino acids. The WW domain of PCIF1 can directly and preferentially bind to the phosphorylated CTD compared to the unphosphorylated CTD. PCIF1 binds to the hyperphosphorylated RNAP II (RNAP IIO) in vitro and in vivo. Double immunofluorescence labeling in HeLa cells demonstrated that PCIF1 and endogenous RNAP IIO are co-localized in the cell nucleus. Thus, PCIF1 may play a role in mRNA synthesis by modulating RNAP IIO activity.
authors.affiliation: Division of Cell Biology, Cancer Research Institute, Kanazawa University, 13-1, Takara-machi, Kanazawa, Ishikawa 920-0934, Japan.
authors.forename: Hong
authors.initials: H
authors.lastname: Fan
authors.forename: Kazumi
authors.initials: K
authors.lastname: Sakuraba
authors.forename: Akihiko
authors.initials: A
authors.lastname: Komuro
authors.forename: Seishi
authors.initials: S
authors.lastname: Kato
authors.forename: Fumio
authors.initials: F
authors.lastname: Harada
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hirose
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D015723:Gene Library; D006367:HeLa Cells; D006801:Humans; D007668:Kidney / Q000166:cytology; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D009687:Nuclear Proteins; C472862:PCIF1 protein, human; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D012319:RNA Polymerase II