Burkey K O, Mathis J N
United States Department of Agriculture-Agricultural Research Service, North Carolina State University, Raleigh 27695-7631, USA.
Plant Physiol. 1998 Feb;116(2):703-8. doi: 10.1104/pp.116.2.703.
Studies were conducted to identify a 64-kD thylakoid membrane protein of unknown function. The protein was extracted from chloroplast thylakoids under low ionic strength conditions and purified to homogeneity by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Four peptides generated from the proteolytic cleavage of the wheat 64-kD protein were sequenced and found to be identical to internal sequences of the chloroplast-coupling factor (CF1) alpha-subunit. Antibodies for the 64-kD protein also recognized the alpha-subunit of CF1. Both the 64-kD protein and the 61-kD CF1 alpha-subunit were present in the monocots barley (Hordeum vulgare), maize (Zea mays), oat (Avena sativa), and wheat (Triticum aestivum); but the dicots pea (Pisum sativum), soybean (Glycine max Merr.), and spinach (Spinacia oleracea) contained only a single polypeptide corresponding to the CF1 alpha-subunit. The 64-kD protein accumulated in response to high irradiance (1000 mumol photons m-2 s-1) and declined in response to low irradiance (80 mumol photons m-2 s-1) treatments. Thus, the 64-kD protein was identified as an irradiance-dependent isoform of the CF1 alpha-subunit found only in monocots. Analysis of purified CF1 complexes showed that the 64-kD protein represented up to 15% of the total CF1 alpha-subunit.
开展了多项研究以鉴定一种功能未知的64千道尔顿类囊体膜蛋白。该蛋白在低离子强度条件下从叶绿体类囊体中提取，并通过制备型十二烷基硫酸钠-聚丙烯酰胺凝胶电泳纯化至同质。对小麦64千道尔顿蛋白经蛋白酶解产生的四个肽段进行了测序，发现它们与叶绿体偶联因子（CF1）α亚基的内部序列相同。针对64千道尔顿蛋白的抗体也识别CF1的α亚基。单子叶植物大麦（Hordeum vulgare）、玉米（Zea mays）、燕麦（Avena sativa）和小麦（Triticum aestivum）中均存在64千道尔顿蛋白和61千道尔顿的CF1α亚基；但双子叶植物豌豆（Pisum sativum）、大豆（Glycine max Merr.）和菠菜（Spinacia oleracea）仅含有一种与CF1α亚基相对应的多肽。64千道尔顿蛋白在高辐照度（1000 μmol光子 m-2 s-1）处理下积累，在低辐照度（80 μmol光子 m-2 s-1）处理下减少。因此，64千道尔顿蛋白被鉴定为仅在单子叶植物中发现的CF1α亚基的辐照度依赖性同工型。对纯化的CF1复合物的分析表明，64千道尔顿蛋白占CF1α亚基总量的比例高达15%。
