Protein Folding in the Eukaryotic Cytosol

描述(由申请人提供)：蛋白质折叠是从基因型到表型的信息流的关键步骤。错误折叠是几种疾病的发病机制的基础，特别是那些涉及神经退化的疾病。我们已经发现了许多促进微管蛋白、肌动蛋白和其他胞质蛋白折叠的伴侣蛋白。这些伴侣蛋白是前折叠蛋白、II型伴侣蛋白CCT和五种称为辅因子A-E的微管蛋白特异性伴侣蛋白。辅因子a)共同发挥微管蛋白二聚体的作用，b)刺激天然微管蛋白异源二聚体的GTP酶活性，将GTP-微管蛋白转化为GDP-微管蛋白。1)我们将通过中和培养细胞中的辅因子功能并分析其对微管细胞骨架的影响来验证后一种反应调节微管动力学的假设。2)我们已经证明了一个称为ARIS(ADP-核糖化因子样蛋白)的小GTP酶家族的成员与微管蛋白和/或微管蛋白特异性伴侣蛋白相互作用。因此，我们建议研究ANL家族成员对辅因子和微管功能的调节。3)我们将研究两种与辅因子相关的人类蛋白RP2和E-like在体外和体外的功能。编码RP2的基因突变会导致视网膜色素变性；E-like的功能尚不清楚。4)我们将分离和鉴定McKusick-Kaufman综合征(MKKS)蛋白，该蛋白被认为是一种新的CCT相关的II型伴侣蛋白，并研究a)其假定的ATPase和伴侣活性，以及b)其结合的靶蛋白的范围。5)我们将检验这样的假设，即CCT的主要功能是打开某些新合成的蛋白质的核苷酸结合口袋，从而允许它们与核苷酸结合。

DESCRIPTION (provided by applicant): Protein folding is a critical step in the flow of information from genotype to phenotype. Misfolding underlies the pathogenesis of several diseases, particularly those involving neurodegeneration. We have discovered many of the chaperone proteins that facilitate the folding of tubulins, actins and other cytosolic proteins. These chaperones are prefoldin, the Type II chaperonin CCT, and five tubulin-specific chaperone proteins termed cofactors A-E. The cofactors a) function together as a tubulin dimer-making machine, and b) stimulate the GTPase activity of the native tubulin heterodimer, converting GTP-tubulin to GDP-tubulin. 1) We will test the hypothesis that the latter reaction regulates microtubule dynamics by neutralizing cofactor function in cultured cells and assaying the effect on the microtubule cytoskeleton. 2) We have shown that members of a family of small GTPases termed Aris (ADP-ribosylation factor-like proteins) interact with tubulin and/or tubulin-specific chaperones. We therefore propose to examine the regulation of cofactor and microtubute function by members of the Anl family. 3) We will investigate the function of two cofactor-related human proteins, RP2 and E-like, in vitro and in vitro. Mutations in the gene encoding RP2 cause retinitis pigmentosa; the function of E-like is unknown. 4) We will isolate and charactenize the McKusick-Kaufman Syndrome (MKKS) protein, which is pnedicted to be a new CCT-related Type II chaperonin, and study a) its presumptive ATPase and chaperone activities, and b) the range of target proteins to which it binds. 5) We will test the hypothesis that that the main function of CCT is to open up the nucleotidebinding pocket of certain newly synthesized proteins, so as to allow them to bind nucleotide.