Runswick M J, Fearnley I M, Skehel J M, Walker J E
Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.
FEBS Lett. 1991 Jul 29;286(1-2):121-4. doi: 10.1016/0014-5793(91)80955-3.
The amino-acid sequence of a subunit of NADH:ubiquinone oxidoreductase from bovine heart mitochondria has been determined and is closely related to those of acyl carrier proteins that are involved in fatty acid biosynthesis in Escherichia coli and plants. Evidence for the presence of covalently attached pantetheine-4'-phosphate in the bovine protein has been obtained by determination of the molecular mass of the isolated subunit by electrospray mass spectrometry, before and after incubation of the protein at alkaline pH under reducing conditions. This decreased the molecular mass from 10,751.6 to 10,449.4, a difference of 302.2 mass units; the value calculated from the protein sequence with one covalently attached pantetheine-4'-phosphate is 10,449.8. The acyl group which is removed by alkaline reduction, appears to be attached via a thioester linkage. By analogy with the bacterial protein it is likely that the attachment site of the pantetheine-4-phosphate is serine-44, which is found in a highly conserved region of the sequence. At present the function of the acyl carrier protein in mitochondrial complex I is not understood.
已确定牛心线粒体中NADH：泛醌氧化还原酶一个亚基的氨基酸序列，它与大肠杆菌和植物中参与脂肪酸生物合成的酰基载体蛋白的氨基酸序列密切相关。通过在还原条件下于碱性pH孵育该蛋白前后，用电喷雾质谱法测定分离出的亚基的分子量，已获得牛蛋白中存在共价连接的泛酰巯基乙胺-4'-磷酸的证据。这使分子量从10,751.6降至10,449.4，相差302.2质量单位；根据具有一个共价连接的泛酰巯基乙胺-4'-磷酸的蛋白质序列计算出的值为10,449.8。通过碱性还原去除的酰基似乎通过硫酯键连接。与细菌蛋白类似，泛酰巯基乙胺-4-磷酸的连接位点可能是丝氨酸-44，它位于序列的一个高度保守区域。目前尚不清楚线粒体复合体I中酰基载体蛋白的功能。
