Naf1 p is a box H/ACA snoRNP assembly factor.
Box H/ACA small nucleolar ribonucleoprotein particles (snoRNPs) contain four essential proteins, Cbf5p, Gar1p, Nhp2p, and Nop10p, each of which, with the exception of Gar1p, is required for box H/ACA snoRNA accumulation. Database searches identified a novel essential protein, which we termed Naf1p, with a region of homology to the RNA-binding domain of Gar1p and other features in common with hnRNP-like proteins. Naf1p is localized to the nucleus and is not a stable component of the H/ACA snoRNPs, but it is required for the accumulation of all box H/ACA snoRNAs. This requirement is not at the level of snoRNA transcription initiation or termination. Naf1 p shows in vitro RNA-binding activity and also binds directly to Cbf5p and Nhp2p. Naf1p was shown to bind to the CTD in vivo in a two-hybrid assay, and the phosphorylated CTD, but not the nonphosphorylated CTD, was shown to precipitate tagged Naf1p from a cell lysate. We propose that Naf1 p is recruited to the CTD of RNA polymerase II and binds to nascent box H/ACA snoRNAs promoting snoRNP assembly.
Pubmed ID: 12515383 RIS Download
Amino Acid Motifs | Amino Acid Sequence | Binding Sites | Cell Nucleus | Fungal Proteins | Hydro-Lyases | Microtubule-Associated Proteins | Molecular Sequence Data | Nuclear Proteins | RNA Polymerase II | RNA Processing, Post-Transcriptional | RNA, Ribosomal | RNA, Small Nucleolar | RNA-Binding Proteins | Recombinant Proteins | Ribonucleoproteins, Small Nuclear | Ribonucleoproteins, Small Nucleolar | Saccharomyces cerevisiae Proteins | Sequence Homology, Amino Acid | Transcription, Genetic | Yeasts