NUCLEOCYTOPLASMIC TRANSPORT

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。蛋白质和核酸的核质运输对细胞的正常运作至关重要。它通过核孔复合体的方式发生，并由一个小的GTP酶Ran控制。最近提出的两个模型(Smith等人，Science(2002)，Gorlich等人，EMBO J(2002))预测了RAN核质运输对RAN鸟嘌呤交换因子RCC1活性的敏感性截然不同，RCC1是一种将RAN转化为细胞核中GTP结合形式的酶。对这些模型的比较分析表明，它们在结构上相似，但具有略有不同的酶活性，特别是RAN进入细胞核的孔渗透率不同20倍。活细胞中的荧光相关光谱(FCS)正被用来直接测量这一途径中各组分的反应速度和流动分数，以评估这些模型中的哪一个最符合实验情况。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Nucleocytoplasmic transport of proteins and nucleic acids is crucial for normal cell functioning. It occurs by way of nuclear pore complexes and is controlled by a small GTPase, Ran. Two recently proposed models (Smith et al., Science (2002), Gorlich et al., EMBO J (2002)) predict very different sensitivity of the Ran nucleocytoplasmic transport to the activity of the Ran guanine exchange factor, RCC1, an enzyme converting Ran to the GTP-bound form in the nucleus. A comparative analysis of the models shows that they are structurally similar but assume somewhat different enzyme activities and, particularly, 20-fold different pore permeability for the Ran entry into the nucleus. Fluorescence correlation spectroscopy (FCS) in live cells is being used to directly measure reaction rates and mobile fractions of components in this pathway to assess which of these models best fit the experimental situation.