Nakagawa T, Maeshima M, Nakamura K, Asahi T
Laboratory of Biochemistry, School of Agriculture, Nagoya University, Japan.
Eur J Biochem. 1990 Aug 17;191(3):557-61. doi: 10.1111/j.1432-1033.1990.tb19157.x.
A cDNA clone for the subunit Vc, the smallest nuclear-encoded subunit, of sweet potato cytochrome c oxidase was isolated. Nucleotide sequence analysis showed that the subunit is synthesized as a precursor from which only the amino-terminal amino acid, methionine, residue is removed to form the mature subunit. The mature subunit consists of 63 amino acid residues which are arranged so as to form one hydrophobic cluster lying between two hydrophilic clusters; such an arrangement is also seen with some nuclear-encoded small subunits of the enzymes from other eukaryotes. The labelled precursor protein was synthesized with the cDNA by in vitro transcription (SP6 system) and translation (wheat germ system). This precursor was imported into isolated sweet potato tuberous root mitochondria without any significant processing, the import being dependent on membrane potential.
分离出了甘薯细胞色素c氧化酶最小的核编码亚基Vc的cDNA克隆。核苷酸序列分析表明，该亚基作为前体合成，只有氨基末端的氨基酸残基甲硫氨酸被去除后形成成熟亚基。成熟亚基由63个氨基酸残基组成，这些氨基酸残基排列形成一个位于两个亲水簇之间的疏水簇；在来自其他真核生物的该酶的一些核编码小亚基中也观察到这种排列。通过体外转录（SP6系统）和翻译（小麦胚芽系统）用该cDNA合成了标记的前体蛋白。这种前体在没有任何显著加工的情况下被导入分离的甘薯块根线粒体中，其导入依赖于膜电位。
