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.
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.
Iida
Reiko
R
Department of Forensic Medicine, Fukui Medical School, Fukui 910-1193, Japan. ireiko@fmsrsa.fukui-med.ac.jp
Yasuda
Toshihiro
T
Tsubota
Etsuko
E
Takatsuka
Hisakazu
H
Masuyama
Mika
M
Matsuki
Takasumi
T
Kishi
Koichiro
K
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
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