In vivo studies of the role of the RanGTPase in post-mitotic nuclear envelope assembly

• Applicant: Professor Dr. Iain W. Mattaj
• Subject Area: Cell Biology
• Term: from 2000 to 2007
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5238698

Nucleocytoplasmic transport requires several activities. These include transport receptors, mainly members of the importin-b protein family, substrates, i.e. the proteins RNAs and RNPs that are transported, and adaptors, that in some cases are required to mediate interaction between a substrate and its transport receptor. The receptors interact specifically with components of the nuclear pore complex (NPC) to mediate NPC translocation. Ran.GTPase regulates the directionality of transport by ensuring that the assembly and disassembly of import and export complexes occurs in the correct cellular compartment. U snRNA export is mediated by CRM1, an export receptor with multiple substrates. Adaptors are also required for U snRNA export; the nuclear Cap-Binding Complex (CBC) and p55 protein. p55 is only functional when phosphorylated. p55 may be dephosphorylated and rephosphorylated for each U snRNA export cycle. This has implications for U snRNA export and the regulation of CRM1 activity. The mechanistic role of p55 phosphorylation, the sites of p55 phosphorylation and the kinase(s) and phosphatase(s) responsible for p55 phosphorylation and dephosphorylation will be studied.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1050: Funktionelle Architektur des Zellkerns