title: M-LP, Mpv17-like protein, has a peroxisomal membrane targeting signal comprising a transmembrane domain and a positively charged loop and up-regulates expression of the manganese superoxide dismutase gene.
abstract: M-LP (Mpv17-like protein) has been identified as a new protein that has high sequence homology with Mpv17 protein, a peroxisomal membrane protein involved in the development of early onset glomerulosclerosis. In this study, we verified the peroxisomal localization of M-LP by performing dual-color confocal analysis of COS-7 cells cotransfected with green fluorescent protein-tagged M-LP and DsRED2-PTS1, a red fluorescent peroxisomal marker. To characterize the peroxisomal membrane targeting signal, we examined the intracellular localizations of several green fluorescent protein-tagged deletion mutants and demonstrated that, of the three transmembrane segments predicted, the first near the NH(2) terminus and NH(2)-terminal half of the following loop region, which is abundant in positively charged amino acids, were necessary and sufficient for peroxisomal targeting. To elucidate the function of M-LP, we examined the activities of several enzymes involved in reactive oxygen species metabolism in COS-7 cells and found that transfection with M-LP increased the superoxide dismutase activity significantly. Quantitative real-time PCR analysis revealed that the manganese SOD (SOD2) mRNA level of COS-7 cells transfected with M-LP was elevated. These results indicate that M-LP participates in reactive oxygen species metabolism.
authors.affiliation: Department of Forensic Medicine, Fukui Medical School, Fukui 910-1193, Japan. ireiko@fmsrsa.fukui-med.ac.jp
authors.forename: Reiko
authors.initials: R
authors.lastname: Iida
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Yasuda
authors.forename: Etsuko
authors.initials: E
authors.lastname: Tsubota
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Takatsuka
authors.forename: Mika
authors.initials: M
authors.lastname: Masuyama
authors.forename: Takasumi
authors.initials: T
authors.lastname: Matsuki
authors.forename: Koichiro
authors.initials: K
authors.lastname: Kishi
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002522:Chlorocebus aethiops; D017931:DNA Primers; D015971:Gene Expression Regulation, Enzymologic; D017930:Genes, Reporter; D005822:Genetic Vectors; D007425:Intracellular Membranes / Q000502:physiology*; D007668:Kidney / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D051379:Mice; D020675:Peroxisomes / Q000502:physiology*; D016133:Polymerase Chain Reaction; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics*; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D020121:5' Untranslated Regions; D017931:DNA Primers; D008565:Membrane Proteins; C427206:Mpv17l protein, mouse; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D013482:Superoxide Dismutase