Histone molar ratios among different electrophoretic forms of mono- and dinucleosomes.
Histone molar ratios among different electrophoretic forms of mono- and dinucleosomes.
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不同电泳形式的单核小体和双核小体之间的组蛋白摩尔比。
DOI：
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发表时间：
1979
影响因子：
4.8
通讯作者：
W. Garrard
中科院分区：
文献类型：
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作者：
S. C. Albright;P. P. Nelson;W. Garrard
已在培养的小鼠细胞的细胞核、染色质以及不同电泳形式的单核小体和双核小体中测定了每种组蛋白类别和蛋白 A24 的相对摩尔比。为此，使用[3H]赖氨酸和[14C]精氨酸标记的细胞进行样品制备，并根据十二烷基硫酸钠（SDS）凝胶电泳后的蛋白质放射性谱和已知氨基酸组成来估计化学计量。结果表明，每个单核小体和每个双核小体分别存在 1 个和 2 个组蛋白 H1 分子的上限。然而，分离的细胞核每个核小体含有少于一个组蛋白 H1 副本。此外，在所研究的染色质亚组分中，组蛋白 H3、H2B 和 H4 基本上是等摩尔的，而组蛋白 H2A 则比等摩尔少 19 +/- 9%。后一个发现为 Goldknopf (Goldknopf, I. L., French, M. F., Musso, R., and Busch, H. (1977) Proc. Natl. Acad. Sci. U. S. A. 74, 5492-5495) 的提议提供了直接支持，即蛋白 A24 取代核小体八聚体蛋白核心中的组蛋白 H2A，因为约 10%培养的小鼠细胞的总组蛋白 H2A 以蛋白 A24 的形式存在，存在于核小体中。根据本研究的结果，得出的结论是，单核小体和双核小体的电泳分级分离不是由于四种较小组蛋白类别的摩尔比或数量的变化，而是部分取决于 DNA 长度、相关组蛋白 H1 分子的数量和非组蛋白染色体蛋白。
The relative molar ratios of each of the histone classes and protein A24 have been determined in nuclei, chromatin, and different electrophoretic forms of mono- and dinucleosomes of cultured mouse cells. For this purpose, [3H]lysine- and [14C]arginine-labeled cells were used for sample preparations, and stoichiometries were estimated from protein radioactivity profiles and known amino acid compositions following sodium dodecyl sulfate (SDS)-gel electrophoresis. The results demonstrate that upper limits of one and two histone H1 molecules exist per mono- and dinucleosome, respectively. However, isolated nuclei contain less than one copy of histone H1 per nucleosome. In addition, among the chromatin subfractions studied, histones H3, H2B, and H4 are essentially equimolar, while histone H2A is less than equimolar by 19 +/- 9%. This latter finding offers direct support to the proposal of Goldknopf (Goldknopf, I. L., French, M. F., Musso, R., and Busch, H. (1977) Proc. Natl. Acad. Sci. U. S. A. 74, 5492-5495) that protein A24 replaces histone H2A in the octamer protein core of the nucleosome, since about 10% of the total histone H2A of cultured mouse cells is in the form of protein A24 and is present in nucleosomes. From the results of the present study, it is concluded that electrophoretic fractionation of mono- and dinucleosomes is not due to variable molar ratios or amounts of the four smaller histone classes, but depends on part on DNA length, the number of associated histone H1 molecules, and non-histone chromosomal proteins.