Goldknopf I L, Taylor C W, Baum R M, Yeoman L C, Olson M O, Prestayko A W, Busch H
J Biol Chem. 1975 Sep 25;250(18):7182-7.
In earlier studies, the nucleolar levels of protein A24 were found to be markedly decreased in the nucleolar hypertrophy induced by thioacetamide or during liver regeneration (Ballal, N.R., Goldknopf, I.L., Goldberg, D.A., and Busch, H. (1974) Life Sci. 14, 1835-1845; Ballal, N.R., Kang, Y.-J., Olson, M.O.-J., and Busch, H.J. Biol. Chem. 250, 5921-5925). To determine the role of protein A24, methods were developed for its isolation in highly purified form. Milligram quantities of highly purified protein A24 were isolated from the 0.4 N H2SO4-soluble proteins of calf thymus chromatin by exclusion chromatography on Sephadex G-100, followed by preparative polyacrylamide gel electrophoresis. Protein A24 was highly purified as shown by its migration as a single spot on two-dimensional polyacrylamide gel electrophoresis, its single NH2-terminal amino acid, methionine, and the production of approximately 50 peptides by tryptic digestion. Like histones 2A, 2B, 3, and 4. A24 was extractable from chromatin with 0.4 N H2SO4 or 3 M NaCl/7 M urea, but unlike most non-histone proteins or histone 1, protein A24 was not extracted with 0.35 M NaCl, 0.5 M HClO4, or 0.6 M NaCl. Protein A24 was present in only 1.9% of the total amount of histones 2A, 2B, 3 and 4; its molecular weight is 27,000.
在早期研究中，发现硫代乙酰胺诱导的核仁肥大或肝脏再生过程中，蛋白质A24的核仁水平显著降低（巴拉尔，N.R.，戈德克诺夫，I.L.，戈德堡，D.A.，和布施，H.（1974年）《生命科学》14卷，1835 - 1845页；巴拉尔，N.R.，康，Y.-J.，奥尔森，M.O.-J.，和布施，H.《生物化学杂志》250卷，5921 - 5925页）。为了确定蛋白质A24的作用，开发了以高纯度形式分离它的方法。通过在Sephadex G - 100上进行排阻色谱，随后进行制备性聚丙烯酰胺凝胶电泳，从牛胸腺染色质的0.4N硫酸可溶性蛋白中分离出了毫克量的高纯度蛋白质A24。二维聚丙烯酰胺凝胶电泳显示蛋白质A24迁移为单个斑点，其单一的氨基末端氨基酸为甲硫氨酸，经胰蛋白酶消化产生约50个肽段，表明蛋白质A24已高度纯化。与组蛋白2A、2B、3和4一样，A24可用0.4N硫酸或3M氯化钠/7M尿素从染色质中提取，但与大多数非组蛋白或组蛋白1不同，蛋白质A24不能用0.35M氯化钠、0.5M高氯酸或0.6M氯化钠提取。蛋白质A24仅占组蛋白2A、2B、3和4总量的1.9%；其分子量为27,000。
