Asher E B, Groudinsky O, Dujardin G, Altamura N, Kermorgant M, Slonimski P P
Centre de Génétique Moléculaire du C.N.R.S., Laboratoire propre associé à l'Université P. et M. Curie, Gif-sur-Yvette, France.
Mol Gen Genet. 1989 Feb;215(3):517-28. doi: 10.1007/BF00427051.
We have cloned three distinct nuclear genes, NAM1, NAM7, and NAM8, which alleviate mitochondrial intron mutations of the cytochrome b and COXI (subunit I of cytochrome oxidase) genes when present on multicopy plasmids. These nuclear genes show no sequence homology to each other and are localized on different chromosomes: NAM1 on chromosome IV, NAM7 on chromosome XIII and NAM8 on chromosome VIII. Sequence analysis of the NAM1 gene shows that it encodes a protein of 440 amino acids with a typical presequence that would target the protein to the mitochondrial matrix. Inactivation of the NAM1 gene by gene transplacement leads to a dramatic reduction of the overall synthesis of mitochondrial protein, and a complete absence of the COXI protein which is the result of a specific block in COXI pre-mRNA splicing. The possible mechanisms by which the NAM1 gene product may function are discussed.
我们克隆了三个不同的核基因，即NAM1、NAM7和NAM8，当它们存在于多拷贝质粒上时，可缓解细胞色素b和COXI（细胞色素氧化酶亚基I）基因的线粒体内含子突变。这些核基因彼此之间没有序列同源性，并且定位在不同的染色体上：NAM1位于第四条染色体上，NAM7位于第十三条染色体上，NAM8位于第八条染色体上。NAM1基因的序列分析表明，它编码一种含有440个氨基酸的蛋白质，带有一个典型的前导序列，该序列可将蛋白质靶向线粒体基质。通过基因置换使NAM1基因失活会导致线粒体蛋白质的总体合成显著减少，并且完全缺失COXI蛋白质，这是COXI前体mRNA剪接中特定阻断的结果。文中讨论了NAM1基因产物可能发挥作用的机制。
