title: Myosin Vb localises to nucleoli and associates with the RNA polymerase I transcription complex.
abstract: It is becoming increasingly clear that the mammalian class V myosins are involved in a wide range of cellular processes such as receptor trafficking, mRNA transport, myelination in oligodendrocytes and cell division. Using paralog-specific antibodies, we observed significant nuclear localisation for both myosin Va and myosin Vb. Myosin Vb was present in nucleoli where it co-localises with RNA polymerase I, and newly synthesised ribosomal RNA (rRNA), indicating that it may play a role in transcription. Indeed, its nucleolar pattern was altered upon treatment with RNA polymerase I inhibitors. In contrast, myosin Va is largely excluded from nucleoli and is unaffected by these inhibitors. Myosin Vb was also found to physically associate with RNA polymerase I and actin in co-immunoprecipitation experiments. We propose that myosin Vb serves a role in rRNA transcription.
authors.affiliation: Molecular Cell Biology Laboratory, Department of Biochemistry, Biosciences Institute, University College Cork, Cork, Ireland.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lindsay
authors.forename: Mary W
authors.initials: MW
authors.lastname: McCaffrey
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D046912:Multiprotein Complexes / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000378:metabolism*; D024701:Myosin Type V / Q000378:metabolism*; D012318:RNA Polymerase I / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology
chemical_list: D000199:Actins; C505832:MYO5B protein, human; D046912:Multiprotein Complexes; D012335:RNA, Ribosomal; C077511:MYO5A protein, human; D012318:RNA Polymerase I; D024701:Myosin Type V; D018995:Myosin Heavy Chains