Hanas J S, Hazuda D J, Bogenhagen D F, Wu F Y, Wu C W
J Biol Chem. 1983 Dec 10;258(23):14120-5.
Transcription factor A from immature Xenopus oocytes is found associated with 5 S RNA in a 7 S nucleoprotein complex. Atomic absorption analysis of EDTA-dialyzed 7 S particles reveals 2 mol of zinc/mol of particle. Factor A obtained from EDTA-dialyzed particles binds specifically to the 5 S RNA gene as determined by DNase I footprinting. Factor A alone, obtained by RNase digestion of the 7 S particle, contains zinc when dialyzed in the absence of EDTA. However, the zinc bound to free factor A is removed by dialysis against a buffer containing EDTA. The apoprotein does not bind to the 5 S RNA gene. Inhibition of footprinting is also effected by addition of EDTA to factor A without prolonged dialysis. Under these conditions, specific DNA binding ability is restored following addition of zinc. 1,10-Phenanthroline also inhibits binding of factor A to the intragenic control region of the 5 S RNA gene. In addition, this reagent specifically inhibits factor A-dependent synthesis of 5 S RNA but not factor A-independent tRNA synthesis in a HeLa cell in vitro transcription system.
在非洲爪蟾未成熟卵母细胞中发现的转录因子A与7S核蛋白复合物中的5S RNA相关联。对经EDTA透析的7S颗粒进行原子吸收分析，结果显示每个颗粒含有2摩尔锌。通过DNase I足迹法测定，从经EDTA透析的颗粒中获得的因子A能特异性结合到5S RNA基因上。单独的因子A是通过对7S颗粒进行RNase消化获得的，在不添加EDTA的情况下进行透析时含有锌。然而，与游离因子A结合的锌可通过用含EDTA的缓冲液透析而去除。脱辅基蛋白不与5S RNA基因结合。在不进行长时间透析的情况下，向因子A中添加EDTA也会抑制足迹法实验结果。在这些条件下，添加锌后可恢复特异性DNA结合能力。1,10 - 菲咯啉也会抑制因子A与5S RNA基因基因内控制区的结合。此外，该试剂在HeLa细胞体外转录系统中能特异性抑制因子A依赖的5S RNA合成，但不抑制因子A非依赖的tRNA合成。
