Terada Kazutoyo, Ueno Shota, Yomogida Kentaro, Imai Tomoaki, Kiyonari Hiroshi, Takeda Naoki, Yano Masato, Abe Shinichi, Aizawa Shinichi, Mori Masataka
Department of Molecular Genetics, Kumamoto University School of Medicine, Honjo 2-2-1, Kumamoto 860-0811, Japan.
J Biochem. 2003 May;133(5):625-31. doi: 10.1093/jb/mvg080.
The 34-kDa translocase of the outer mitochondrial membrane (Tom34) is a putative mammalian-specific factor involved in protein import into mitochondria. We analyzed the genomic sequence of the mouse Tom34 gene and found it has two alternative initial exons. Using reverse transcription and the polymerase chain reaction (RT-PCR), we found that these two mRNAs differs only in the 5'-proximal sequences corresponding to the two initial exons (exon 1a and 1b). Tom34 mRNA with exon 1a (Tom34a) is expressed ubiquitously, while that with exon 1b (Tom34b) is expressed only in mature testicular germ cells. To explore the in vivo function of Tom34 proteins, we generated Tom34-deficient mice by targeted disruption. The Tom34(-/-) mice were viable and grew normally and had a normal Mendelian inheritance pattern. Male as well as female Tom34(-/-) mice were fertile. In vitro-preprotein import into isolated mitochondria showed no apparent difference between Tom34(-/-) and wild-type mice. These results indicate that Tom34 is dispensable for mouse growth and development under optimal conditions.
线粒体外膜34 kDa转位酶（Tom34）是一种推测参与蛋白质导入线粒体的哺乳动物特异性因子。我们分析了小鼠Tom34基因的基因组序列，发现它有两个可变的起始外显子。利用逆转录和聚合酶链反应（RT-PCR），我们发现这两种mRNA仅在对应于两个起始外显子（外显子1a和1b）的5'近端序列上有所不同。含有外显子1a的Tom34 mRNA（Tom34a）在各处均有表达，而含有外显子1b的Tom34 mRNA（Tom34b）仅在成熟的睾丸生殖细胞中表达。为了探究Tom34蛋白的体内功能，我们通过靶向破坏产生了Tom34基因敲除小鼠。Tom34（-/-）小鼠存活且生长正常，具有正常的孟德尔遗传模式。雄性和雌性Tom34（-/-）小鼠均具有生育能力。体外前体蛋白导入分离的线粒体的实验表明，Tom34（-/-）小鼠和野生型小鼠之间没有明显差异。这些结果表明，在最佳条件下，Tom34对小鼠的生长发育并非必需。
