Expression and differential intracellular localization of two major forms of human 8-oxoguanine DNA glycosylase encoded by alternatively spliced OGG1 mRNAs
Expression and differential intracellular localization of two major forms of human 8-oxoguanine DNA glycosylase encoded by alternatively spliced OGG1 mRNAs
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DOI：
10.1091/mbc.10.5.1637
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发表时间：
1999-05-01
影响因子：
3.3
通讯作者：
Nakabeppu, Y
中科院分区：
文献类型：
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作者：
Nishioka, K;Ohtsubo, T;Nakabeppu, Y
我们鉴定了7种人类8-氧代鸟嘌呤DNA糖基化酶（OGG 1）mRNA的可变剪接形式，根据其最后一个外显子分为两种类型（1型外显子7：1a和1b; 2型外显子8：2a至2 e）。Ia型和2a型mRNA主要存在于人体组织中。预期7种mRNA编码不同的多肽（OGG 1 -1a至2 e），这些多肽与共同的线粒体靶向信号共享其N末端，并且每个具有独特的C末端。从核提取物中共纯化了一种36-kDa多肽，其对应于OGG 1 -1a，仅被针对含有螺旋-发夹-螺旋-PVD基序的区域的抗体识别，具有将切口引入含有8-氧代鸟嘌呤的DNA的活性。一个40-kDa的多肽对应于一个加工形式的OGG 1 -2a的检测在他们的线粒体中使用抗体对其C端。电镜免疫细胞化学和线粒体亚分级显示OGG 1 -2a定位于线粒体内膜。缺失突变体分析表明，OGG 1 -2a独特的C末端及其线粒体靶向信号对线粒体定位至关重要，OGG 1 -1a的核定位依赖于其C末端的NLS。
We identified seven alternatively spliced forms of human 8-oxoguanine DNA glycosylase (OGG1) mRNAs, classified into two types based on their last exons (type 1 with exon 7: 1a and 1b; type 2 with exon 8: 2a to 2e). Types la and 2a mRNAs are major in human tissues. Seven mRNAs are expected to encode different polypeptides (OGG1-1a to 2e) that share their N terminus with the common mitochondrial targeting signal, and each possesses a unique C terminus. A 36-kDa polypeptide, corresponding to OGG1-1a recognized only by antibodies against the region containing helix-hairpin-helix-PVD motif, was copurified from the nuclear extract with an activity introducing a nick into DNA containing 8-oxoguanine. A 40-kDa polypeptide corresponding to a processed form of OGG1-2a was detected in their mitochondria using antibodies against its C terminus. Electron microscopic immunocytochemistry and subfractionation of the mitochondria revealed that OGG1-2a locates on the inner membrane of mitochondria. Deletion mutant analyses revealed that the unique C terminus of OGG1-2a and its mitochondrial targeting signal are essential for mitochondrial localization and that nuclear localization of OGG1-1a depends on the NLS at its C terminus.