Goldknopf I L, French M F, Musso R, Busch H
Proc Natl Acad Sci U S A. 1977 Dec;74(12):5492-5. doi: 10.1073/pnas.74.12.5492.
Two-dimensional gel profiles of the 0.2 M H2SO4-soluble proteins of monomer nucleosomal fractions were found to contain protein A24. Protein A24 is of interest because it is composed of histone 2A and "ubiquitin", apparently joined by an isopeptide linkage [Goldknopf, I.L. & Busch, H. (1977) Proc. Natl. Acad. Sci. USA 74, 864-868; Hunt, L.T. & Dayhoff, M.O. (1977) Biochem. Biophys. Res. Commun. 74, 650-655]. Monomer nucleosomal fractions were obtained by sucrose density gradient centrifugation of micrococcal nuclease digests of rat liver nuclei. As shown by their DNA size, the monomer fractions were highly purified. Proteins A24 and Bu, another protein of unknown characteristics, were found along with histones 1, 2A, 2B, 3, and 4 in the monomer fractions in relative amounts similar to those found in extracts from whole nuclei and chromatin. Other acid-soluble proteins found in the nuclear and chromatin extracts were essentially absent from the monomer fraction. Inasmuch as protein A24 and Bu were found in lesser amounts than the histones, it is suggested that they are associated with specialized subsets of nucleosomes.
单体核小体组分中0.2M硫酸可溶蛋白的二维凝胶图谱显示含有蛋白质A24。蛋白质A24备受关注，因为它由组蛋白2A和“泛素”组成，显然是通过异肽键连接的[戈德克诺夫，I.L. & 布施，H.（1977年）《美国国家科学院院刊》74，864 - 868；亨特，L.T. & 戴霍夫，M.O.（1977年）《生物化学与生物物理研究通讯》74，650 - 655]。通过对大鼠肝细胞核微球菌核酸酶消化产物进行蔗糖密度梯度离心获得单体核小体组分。从其DNA大小可以看出，单体组分得到了高度纯化。在单体组分中发现了蛋白质A24和另一种特性不明的蛋白质Bu，以及组蛋白1、2A、2B、3和4，其相对含量与在全细胞核和染色质提取物中发现的相似。在细胞核和染色质提取物中发现的其他酸溶性蛋白质在单体组分中基本不存在。由于发现蛋白质A24和Bu的含量比组蛋白少，所以推测它们与核小体的特定亚组相关。
