What is the role of Ran GTPase in nuclear import?
Ran plays a key role in controlling nucleocytoplasmic trafficking, a process in which many accessory proteins involved in nuclear import and export pathways have also been implicated. It is clear that RanGTPase is crucial for both the nuclear import and export processes.
How is the Ran-GTP complex related to nuclear transport?
Nuclear export Ran-GTP binds GAP and hydrolyzes GTP, and the resulting Ran-GDP complex is restored to the nucleus where it exchanges its bound ligand for GTP. Hence, whereas importins depend on RanGTP to dissociate from their cargo, exportins require RanGTP in order to bind to their cargo.
What is the role of Ran G proteins in nuclear translocation?
Ran is a small G protein that is essential for the translocation of RNA and proteins through the nuclear pore complex. The Ran protein has also been implicated in the control of DNA synthesis and cell cycle progression, as mutations in Ran have been found to disrupt DNA synthesis.
How does nuclear GEF convert Ran-GTP to GDP?
Conversion between the two states is triggered by two Ran-specific regulatory proteins: a cytosolic GTPase-activating protein (GAP) that triggers GTP hydrolysis and thus converts Ran-GTP to Ran-GDP, and a nuclear guanine exchange factor (GEF) that promotes the exchange of GDP for GTP and thus converts Ran-GDP to Ran- …
What is function of Ran GTP?
A key function of the nuclear Ran. GTP is to support formation of complexes containing an export receptor (an exportin) and cargos such as RNAs, RNPs or proteins that are destined for export. In the cytoplasm, removal of the Ran. GTP from the complex results in its destabilization and release of the export cargo.
What does Ran GTP do?
The small GTPase Ran regulates the interaction of transport receptors with a number of cellular cargo proteins. The high affinity binding of the GTP-bound form of Ran to import receptors promotes cargo release, whereas its binding to export receptors stabilizes their interaction with the cargo.
What does Ran GTP bind to?
Ran binds either GTP or GDP and shuttles between the nucleus and cytoplasm. As a GTPase, Ran hydrolyzes bound GTP into GDP.
What is function of Ran-GTP?
What does Ran-GTP bind to?
What is the function of ran GEF?
For example, the Ran GEF, RCC1, is present in the nucleus while the Ran GAP is present in the cytosol, modulating nuclear import and export of proteins. RCC1 converts RanGDP to RanGTP in the nucleus, activating Ran for the export of proteins.
Why is Ran-GTP concentrated in the nucleus?
The high concentration of Ran-GTP in the nucleus promotes the disassembly of nuclear import complexes between proteins carrying a leucine-rich nuclear export signal (NES) and the transport factor Crm1, while dissociating nuclear import complexes formed between importins and cargo proteins carrying a lysine-rich nuclear …
What does Ran-GTP do?