title: Nucleolar localization of human methionyl-tRNA synthetase and its role in ribosomal RNA synthesis.
abstract: Human aminoacyl-tRNA synthetases (ARSs) are normally located in cytoplasm and are involved in protein synthesis. In the present work, we found that human methionyl-tRNA synthetase (MRS) was translocated to nucleolus in proliferative cells, but disappeared in quiescent cells. The nucleolar localization of MRS was triggered by various growth factors such as insulin, PDGF, and EGF. The presence of MRS in nucleoli depended on the integrity of RNA and the activity of RNA polymerase I in the nucleolus. The ribosomal RNA synthesis was specifically decreased by the treatment of anti-MRS antibody as determined by nuclear run-on assay and immunostaining with anti-Br antibody after incorporating Br-UTP into nascent RNA. Thus, human MRS plays a role in the biogenesis of rRNA in nucleoli, while it is catalytically involved in protein synthesis in cytoplasm.
authors.affiliation: National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Jangangu, Suwon, Kyunggido 440-746, Korea.
authors.forename: Y G
authors.initials: YG
authors.lastname: Ko
authors.forename: Y S
authors.initials: YS
authors.lastname: Kang
authors.forename: E K
authors.initials: EK
authors.lastname: Kim
authors.forename: S G
authors.initials: SG
authors.lastname: Park
authors.forename: S
authors.initials: S
authors.lastname: Kim
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002455:Cell Division; D002466:Cell Nucleolus / Q000201:enzymology*; D002478:Cells, Cultured; D003856:Deoxyuracil Nucleotides / Q000276:immunology / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D007328:Insulin / Q000494:pharmacology; D008718:Methionine-tRNA Ligase / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D012318:RNA Polymerase I / Q000378:metabolism; D015138:RNA, Nuclear / Q000737:chemistry; D012335:RNA, Ribosomal / Q000096:biosynthesis*
chemical_list: D000906:Antibodies; D003856:Deoxyuracil Nucleotides; D007328:Insulin; D009687:Nuclear Proteins; D010982:Platelet-Derived Growth Factor; D015138:RNA, Nuclear; D012335:RNA, Ribosomal; C032549:bromodeoxyuridine triphosphate; D004815:Epidermal Growth Factor; D012318:RNA Polymerase I; D008718:Methionine-tRNA Ligase