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

• Published in: The Journal of biological chemistry 2003-02, Vol.278 (8), p.6301-6306
• Main Authors: Iida, Reiko, Yasuda, Toshihiro, Tsubota, Etsuko, Takatsuka, Hisakazu, Masuyama, Mika, Matsuki, Takasumi, Kishi, Koichiro
• Format: Article
• Language: English
• Subjects: 5' Untranslated Regions - genetics; Animals; Base Sequence; Chlorocebus aethiops; COS Cells; DNA Primers; Gene Expression Regulation, Enzymologic; Genes, Reporter; Genetic Vectors; Intracellular Membranes - physiology; Kidney - metabolism; Membrane Proteins - chemistry; Membrane Proteins - metabolism; Mice; Peroxisomes - physiology; Polymerase Chain Reaction; Protein Structure, Secondary; Reactive Oxygen Species - metabolism; Recombinant Fusion Proteins - metabolism; RNA, Messenger - genetics; Superoxide Dismutase - genetics; Transcription, Genetic; Transfection
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M210886200

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.