title: Different isoforms of PRIP-interacting protein with methyltransferase domain/trimethylguanosine synthase localizes to the cytoplasm and nucleus.
abstract: A protein family including the recently identified PIMT/Tgs1 (PRIP-interacting protein with methyltransferase domain/trimethylguanosine synthase) was identified by searching databases for homologues of a newly identified Drosophila protein with RNA-binding activity and methyltransferase domain. Antibodies raised against a short peptide of the mammalian homologue show a 90-kDa isoform expressed specifically in rat brain and testis and a 55-kDa form expressed ubiquitously. In HeLa cells, the larger isoform of the protein is nuclear and associated with a 600-kDa complex, while the smaller isoform is mainly cytoplasmic and co-localizes to the tubulin network. Inhibition of PIMT/Tgs1 expression by siRNA in HeLa cells resulted in an increase in the percentage of cells in G2/M phases. In yeast two-hybrid and in vitro GST pull down experiments, the conserved C-terminal region of PIMT/Tgs1 interacted with the WD domain containing EED/WAIT-1 that acts as a polycomb-type repressor in the nucleus and also binds to integrins in the cytoplasm. Our experiments, together with earlier data, indicate that isoforms of the PIMT/Tgs1 protein with an RNA methyltransferase domain function both in the nucleus and in the cytoplasm and associate with both elements of the cytoskeletal network and nuclear factors known to be involved in gene regulation.
authors.affiliation: Institute of Biochemistry, Szeged, Hungary.
authors.forename: Izzet
authors.initials: I
authors.lastname: Enünlü
authors.forename: Gábor
authors.initials: G
authors.lastname: Pápai
authors.forename: Imre
authors.initials: I
authors.lastname: Cserpán
authors.forename: Andor
authors.initials: A
authors.lastname: Udvardy
authors.forename: Kuan-Teh
authors.initials: KT
authors.lastname: Jeang
authors.forename: Imre
authors.initials: I
authors.lastname: Boros
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D019992:Databases as Topic; D015536:Down-Regulation; D004330:Drosophila; D016195:G2 Phase; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D008297:Male; D008780:Methyltransferases / Q000737:chemistry* / Q000378:metabolism; D008938:Mitosis; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011485:Protein Binding; D026601:Protein D-Aspartate-L-Isoaspartate Methyltransferase / Q000737:chemistry*; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D017386:Sequence Homology, Amino Acid; D013737:Testis / Q000378:metabolism; D014018:Tissue Distribution; D014404:Tubulin / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D020033:Protein Isoforms; D034741:RNA, Small Interfering; D014404:Tubulin; D008780:Methyltransferases; C456271:trimethylguanosine synthase; C435725:PCMT1 protein, human; D026601:Protein D-Aspartate-L-Isoaspartate Methyltransferase; D005982:Glutathione Transferase