PROTEIN FOLDING IN THE EUKARYOTIC CYTOSOL

描述：分子伴侣是普遍存在的多亚基环状ATPase 使蛋白质折叠变得容易。在真核细胞胞浆中，胞浆 肌动蛋白和肌动蛋白的易化折叠需要辣椒素(c-cpn)。 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生成的折叠中间体，并且是 天然a-微管蛋白和b-微管蛋白的体外形成。1)他们将使用 结合生化、细胞生物学和遗传学方法来测试 相互关联的假设一)在微管蛋白异二聚体中，a-和b- 微管蛋白多肽不以热力学最低能量存在 状态，并认为余因的作用是形成和维持这种状态 激活状态，以及ii)辅因子相互作用的级联 导致从未折叠到天然的a-微管蛋白和b-微管蛋白聚合，因为 每个亚基都需要另一个亚基才能正确折叠。2)他们会 获取有关辅因数的结构数据。3)他们将调查 观察到三种微管蛋白的功能意义 折叠因子通过a)检查它们的微管起到映射的作用 在体外和体内结合的概率，以及b)建立其 微管蛋白合成中潜在的调节作用。4)他们会的 描述一种新发现的提高c-cpn效率的活动。 5)他们已经证明，只有c-cpn(而不是它的原核或 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，他们建议测试假设 C-cpn以外的伴侣蛋白具有有限的靶标范围 C-cpn、线粒体伴侣蛋白Hsp60/Hsp10和 原核生物伴侣蛋白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.