A third isoform of cytochrome c oxidase subunit VIII is present in mammals
A third isoform of cytochrome c oxidase subunit VIII is present in mammals
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DOI：
10.1016/s0378-1119(03)00604-8
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发表时间：
2003-07-17
期刊：
影响因子：
3.5
通讯作者：
Grossman, LI
中科院分区：
文献类型：
--
作者：
Hüttemann, M;Schmidt, TR;Grossman, LI
哺乳动物线粒体呼吸链的末端酶细胞色素c氧化酶（COX）含有3个线粒体亚基和10个核编码亚基。三个核亚基（VIa， VIIa和VIII）具有肌肉和非mu鳞特异性亚型，亚基IV包含肺特异性亚型，亚基VIb包含睾丸特异性亚型。对于亚基VIII，最小的核编码COX多肽，我们现在已经发现了第三个基因（COX 8-3），已在人类，狐猴，大鼠和小鼠中发现，这表明它存在于广泛的真兽哺乳动物中。序列相似性和基因结构支持COX8-3与其他亚基VIII亚型的同源性，表明这三个亚型都是基因复制的产物。COX VIII-3蛋白是线粒体靶向的，通过COX VIII3/DsRed荧光融合蛋白显示。线粒体靶向及其序列保守表明，COX - viii -3作为COX全酶的一部分起作用，可能具有组织特异性作用，其他两个同种异构体也是如此。关于COX8-3主要在哪里表达的问题仍然存在。然而，对全长cdna的检测，第一和第二密码子位置的序列差异水平低于第三密码子位置，以及保守的基因结构表明，COX VIII-3是一个起源至少可追溯到9100万年前的表达基因。(C) 2003 Elsevier Science B.V.版权所有
The terminal enzyme of the mitochondrial respiratory chain, cytochrome c oxidase (COX), contains three mitochondrial and ten nuclear encoded subunits in mammals. Three of the nuclear subunits (VIa, VIIa, and VIII) have muscle and non-mu scle-specific isoforms, subunit IV contains a lung-specific isoform, and subunit VIb contains a testes-specific isoform. For subunit VIII, the smallest nuclear encoded COX polypeptide, we have now found a third gene (COX 8-3), which has been identified in human, lemur, rat, and mouse, suggesting that it is present in a broad range of Eutherian mammals. Sequence similarity and gene structure support the homology of COX8-3 to the other subunit VIII isoforms, indicating that all three are the product of gene duplications. COX VIII-3 protein is mitochondrially-targeted, as shown by a fluorescent COX VIII3/DsRed fusion protein. Both the mitochondrial targeting and its sequence conservation suggest that COXVIII-3 functions as part of the COX holoenzyme and could have a tissue-specific role, as is the case for the other two isoforms. Questions remain about where COX8-3 is predominantly expressed. However, detection of full-length cDNAs, lower levels of sequence divergence at the first and second codon positions compared to the third, and a conserved gene structure indicate that COX VIII-3 is an expressed gene whose origin dates to at least 91 million years ago. (C) 2003 Elsevier Science B.V. All rights reserved.