Biochemical and cellular functions of Karyopherins

朱克实验室旨在了解Karyopherin-蛋白如何识别的机制 有约束力的合作伙伴和地图合作伙伴/货物剧目。我们的目标是了解核细胞质 运输，其他核粘附素功能，并发现它们如何组织和调节细胞功能，在 无论是健康还是疾病。20个同源人类和14个酿酒酵母Kaps介导了大部分核 运输。我们对导入核黄素-β-2进行了广泛的研究。我们发现了PY-NLS 认识到这一信号的物理组织，并设计了第一个核进口 抑制剂。Karyopherin-β2和其他特征良好的重要蛋白、Importin-/β、Importin-5和 Transportin-SR，具有明显的特异性，并结合完全不同的NLS类型。然而，剩下的 重要蛋白：Importin-4、Importin-7、Importin-8、Importin-9和Importin-11正在研究中，很少 已知的货物。货物的稀缺性阻碍了对其生物化学/结构的比较定义 NLSS。我们的目标是为未被研究的重要蛋白发现新的货物和NLSS类别，并绘制 他们控制的交通。我们发现，除了进口货物外，进口素还充当 阻止RNA结合蛋白聚集或作为组蛋白伴侣阻止组蛋白H_2A-H_2B 聚集并协助核小体组装。我们将讨论KAP2分子伴侣的作用机制 功能，以及Kap114如何在典型组蛋白存在的情况下导入和伴侣H_2A-H_2B 监护人。在研究核出口方面，我们为理解 CRM1是如何结合Ness和小分子抑制剂的，但鉴于CRM1的S，还有更多的问题 在许多细胞过程和疾病状态中的重要性。CRM1抑制剂Selinexor诱导细胞凋亡 目前尚不清楚哪些物质是不同癌症的靶点。大多数&gt；1000 含有NES的CRM1货物尚不清楚。准确的NES预测可以帮助识别新的货物， 但不同的NES序列和描述在大多数螺旋中普遍存在的序列的模糊共识- 含有蛋白质使得基于序列的NES预测效率低下。为了改善预测，我们正在 开发一种基于结构和能量的NES预测器。我们还将研究CRM1是如何在 对抑制剂的反应，了解致癌CRM1 E571K突变如何影响NES结合 和CRM1介导的流量，并研究CRM1介导的信使核糖核酸输出。最后，我们将扩大我们的研究范围 与Exportin MSN5结合，它结合了多个 货物，因此是一个很好的系统来定义一个新的NES类别。

The Chook Laboratory aims to understand mechanisms of how Karyopherin- proteins recognize binding partners and map partner/cargo repertoires. We aim to understand nuclear-cytoplasmic transport, other karyopherin functions, and discover how they organize and regulate cellular functions, in health and in disease. 20 homologous human and 14 S. cerevisiae Kaps mediate the majority of nuclear transport. We have studied the importin Karyopherin-β2 extensively. We discovered the PY-NLS that it recognizes, characterized the physical organization of this signal and designed the first nuclear import inhibitor. Karyopherin-β2 and other well-characterized importins, Importin-/β, Importin-5 and Transportin-SR, have distinct specificities and bind entirely different NLS types. However, the remaining importins: Importin-4, Importin-7, Importin-8, Importin-9 and Importin-11, are under-studied with few known cargos. Scarcity of cargos has prevented comparative biochemical/structural definition of their NLSs. We aim to discover new cargos and classes of NLSs for understudied importins and map the traffic they control. We showed that in addition to importing cargos, importins also act as chaperones to prevent aggregation of RNA-binding proteins or act as histone chaperone to prevent histone H2A-H2B aggregation and assist in nucleosome assembly. We will address the mechanism of Kap2 chaperone functions, and how Kap114 imports and chaperones H2A-H2B in the presence of canonical histone chaperones. In the study of nuclear export, we have contributed significantly to the understanding of how CRM1 binds NESs and small molecule inhibitors, but there are many more questions given CRM1’s importance in many cellular processes and disease states. CRM1 inhibitor Selinexor causes apoptosis of cancer cells, but it is not known which cargos are targeted in different cancers. Most of the >1000 NES-containing CRM1 cargos are not known. Accurate NES prediction could help identify new cargos, but diverse NES sequences and vague consensus that describes sequences ubiquitous in most helix- containing proteins make sequence-based NES prediction inefficient. To improve prediction, we are developing a structure- and energy-based NES predictor. We will also study how CRM1 is degraded in response to inhibitors, understand how the oncogenic E571K mutation of CRM1 affects NES-binding and CRM1-mediated traffic, and study CRM1-mediated mRNA export. Finally, we will expand our study to the exportin Msn5, which binds intrinsically disordered and phosphorylated segments of multiple cargos, hence an excellent system to define a new NES class.