title: HMRF1L is a human mitochondrial translation release factor involved in the decoding of the termination codons UAA and UAG.
abstract: While all essential mammalian mitochondrial factors involved in the initiation and elongation phases of translation have been cloned and well characterized, little is known about the factors involved in the termination process. In the present work, we report the functional analysis of human mitochondrial translation release factors (RF). Here, we show that HMRF1, which had been previously denoted as a human mitochondrial RF, was inactive in in vitro translation system, although it is a mitochondrial protein. Instead, we identified another human mitochondrial RF candidate, HMRF1L, and demonstrated that HMRF1L is indeed a mitochondrial protein that functions specifically as an RF for the decoding of mitochondrial UAA and UAG termination codons in vitro. The identification of the functional mitochondrial RF brings us much closer to a detailed understanding of the translational termination process in mammalian mitochondria as well as to the unraveling of the molecular mechanism of diseases caused by the dys-regulation of translational termination in human mitochondria.
authors.affiliation: Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, Building FSB-401, 5-1-5, Kashiwanoha, Kashiwa, Chiba Prefecture 277-8562, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nozaki
authors.forename: Noriko
authors.initials: N
authors.lastname: Matsunaga
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ishizawa
authors.forename: Takuya
authors.initials: T
authors.lastname: Ueda
authors.forename: Nono
authors.initials: N
authors.lastname: Takeuchi
mesh_terms: D002474:Cell-Free System; D018388:Codon, Terminator; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000737:chemistry* / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism*; D010454:Peptide Termination Factors; D014176:Protein Biosynthesis; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D018388:Codon, Terminator; C523958:MTRF1L protein, human; D024101:Mitochondrial Proteins; D010454:Peptide Termination Factors; D014157:Transcription Factors