Chang C, Gonzalez F, Rothermel B, Sun L, Johnston S A, Kodadek T
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8573, USA.
J Biol Chem. 2001 Aug 17;276(33):30956-63. doi: 10.1074/jbc.M102254200. Epub 2001 Jun 19.
An in vivo protein interaction assay was used to search a yeast cDNA library for proteins that bind to the acidic activation domain (AD) of the yeast Gal4 protein. Sug2 protein, a component of the 19 S regulatory particle of the 26 S proteasome, was one of seven proteins identified in this screen. In vitro binding assays confirm a direct interaction between these proteins. SUG2 and SUG1, another 19 S component, were originally discovered as a mutation able to suppress the phenotype of a Gal4 truncation mutant (Gal4(D)p) lacking much of its AD. Sug1p has previously been shown to bind the Gal4 AD in vitro. Taken together, these genetic and biochemical data suggest a biologically significant interaction between the Gal4 protein and the 19 S regulatory particle of the proteasome. Indeed, it is demonstrated here that the Gal4 AD interacts specifically with immunopurified 19 S complex. The proteasome regulatory particle has been shown recently to play a direct role in RNA polymerase II transcription and the activator-19 S interaction could be important in recruiting this large complex to transcriptionally active GAL genes.
利用体内蛋白质相互作用分析方法，在酵母cDNA文库中筛选与酵母Gal4蛋白酸性激活结构域（AD）结合的蛋白质。Sug2蛋白是26S蛋白酶体19S调节颗粒的一个组成部分，是在此筛选中鉴定出的七种蛋白质之一。体外结合分析证实了这些蛋白质之间的直接相互作用。SUG2和SUG1（另一个19S组分）最初是作为一种能够抑制缺乏大部分AD的Gal4截短突变体（Gal4(D)p）表型的突变被发现的。此前已表明Sug1p在体外可与Gal4 AD结合。综合这些遗传和生化数据表明，Gal4蛋白与蛋白酶体的19S调节颗粒之间存在生物学上显著的相互作用。事实上，本文证明Gal4 AD与免疫纯化的19S复合物特异性相互作用。最近已表明蛋白酶体调节颗粒在RNA聚合酶II转录中起直接作用，激活剂与19S的相互作用可能在将这个大复合物募集到转录活跃的GAL基因中起重要作用。
