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 a peroxisomal membrane targeting signal comprising a transmembrane domain and a positively charged loop and up-regulates expression of the manganese superoxide dismutase gene
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DOI：
10.1074/jbc.m210886200
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发表时间：
2003-02-21
影响因子：
4.8
通讯作者：
Kishi, K
中科院分区：
文献类型：
--
作者：
Iida, R;Yasuda, T;Kishi, K
M-LP（Mpv 17-like protein）是一种与Mpv 17蛋白具有高度同源性的新蛋白质，Mpv 17蛋白是一种参与早发性肾小球硬化形成的过氧化物酶体膜蛋白。在这项研究中，我们验证了过氧化物酶体定位的M-LP进行双色共聚焦分析的COS-7细胞共转染绿色荧光蛋白标记的M-LP和DsRED 2-PTS 1，一个红色荧光过氧化物酶体标记。为了表征过氧化物酶体膜靶向信号，我们研究了几个绿色荧光蛋白标记的缺失突变体的细胞内定位，并证明了预测的三个跨膜片段中，第一个靠近NH 2末端和NH 2末端的以下环区域的一半，该区域富含带正电荷的氨基酸，对于过氧化物酶体靶向是必要的和足够的。为了阐明M-LP的功能，我们检测了COS-7细胞中参与活性氧代谢的几种酶的活性，发现转染M-LP显著提高了超氧化物歧化酶的活性。实时荧光定量PCR分析显示，转染M-LP的COS-7细胞锰SOD（SOD 2）mRNA水平升高。这些结果表明，M-LP参与活性氧代谢。
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 NH2 terminus and NH2-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.