PROTEIN FOLDING IN THE EUKARYOTIC CYTOSOL

描述：伴侣蛋白是普遍存在的多亚基环形ATP酶 促进蛋白质折叠。 在真核细胞胞质溶胶中， caperonin（c-cpn）是肌动蛋白折叠所必需的， 微管蛋白 PI发现了五种蛋白质辅因子（称为A-E） 作用于c-cpn产生的折叠中间体， 体外天然a-和B-微管蛋白的形成。1)他们将使用 结合生物化学、细胞生物学和遗传学方法， 相关假设i）在微管蛋白异二聚体中，a-和B- 微管蛋白多肽并不以最低的能量存在 状态，而辅因子的功能是形成和维持这种状态。 活化状态，以及ii）辅因子相互作用的级联 导致从未折叠到天然a-和B-微管蛋白会聚，因为 每个亚基需要另一个亚基才能正确折叠。 2)他们将 获得辅因子的结构数据。3)他们会调查 功能意义的观察，三个微管蛋白 折叠辅因子通过以下方式表现为MAP：a）检查它们的微管 体外和体内结合概率，和B）建立它们的 微管蛋白合成的潜在调节作用。4)他们将 表征新发现的增强c-CPN效率的活性。 5)他们已经表明，只有c-cpn（而不是其原核或 线粒体同源物）可以促进肌动蛋白的生产性折叠 和微管蛋白。 因此，他们提议检验以下假设： 除了c-CPN之外的伴侣蛋白具有有限的靶范围 c-cpn、线粒体伴侣蛋白Hsp 60/Hsp 10和线粒体膜蛋白Hsp 60/Hsp 10的表达水平均明显高于对照组。 原核分子伴侣蛋白GroEL/GroES相互替代， 体外和体内。

DESCRIPTION: Chaperonins are ubiquitous multisubunit toroidal ATPases that faciliate protein folding. In the eukaryotic cytosol, cytosolic caperonin (c-cpn) is required for the faciliated folding of actins and tubulins. The PI has discovered five protein cofactors (termed A-E) that act on c-cpn-generated folding intermediates and are required for the formation of native a- and b- tubulin in vitro. 1) They will use combined biochemical, cell biological and genetic approaches to test the interrelated hypotheses i)that in the tubulin heterodimer, a- and b- tubulin polypeptides do not exist in a thermodynamically minimal energy state, and that the function of cofactors is to form and maintain this activated state, and ii) that the cascade of cofactor interactions leading from unfolded to native a- and b- tubulin converge, because each subunit requires the other in order to fold properly. 2)They will obtain structural data on the cofactors. 3) They will investigate the functional significance of the observation that three of the tubulin folding confactors behave as MAPs by a) examining their microtubule binding probperties in vitro and in vivo, and b) establishing their potential regulatory role in tubulin synthesis. 4) They will characterize a newly discovered activity that enhances c-cpn efficiency. 5) They have shown that only c-cpn (and not its prokaryotic or mitochondrial homologs) can facilitate the productive folding of actins and tubulins. They therefore propose to test the hypotheis that chaperonins other than c-cpn have a restricted target range by examining the abitlity of c-cpn, the mitochondrial chaperonin Hsp60/Hsp10, and the prokaryotic chaperonin GroEL/GroES to substitute for one another in vitro and in vivo.