1qg2
From Proteopedia
CANINE GDP-RAN R76E MUTANT
Structural highlights
FunctionRAN_CANLF GTPase involved in nucleocytoplasmic transport, participating both to the import and the export from the nucleus of proteins and RNAs. Switches between a cytoplasmic GDP- and a nuclear GTP-bound state by nucleotide exchange and GTP hydrolysis. Nuclear import receptors such as importin beta bind their substrates only in the absence of GTP-bound RAN and release them upon direct interaction with GTP-bound RAN, while export receptors behave in the opposite way. Thereby, RAN controls cargo loading and release by transport receptors in the proper compartment and ensures the directionality of the transport. Interaction with RANBP1 induces a conformation change in the complex formed by XPO1 and RAN that triggers the release of the nuclear export signal of cargo proteins. RAN (GTP-bound form) triggers microtubule assembly at mitotic chromosomes and is required for normal mitotic spindle assembly and chromosome segregation. Required for normal progress through mitosis. The complex with BIRC5/survivin plays a role in mitotic spindle formation by serving as a physical scaffold to help deliver the RAN effector molecule TPX2 to microtubules. Acts as a negative regulator of the kinase activity of VRK1 and VRK2. Enhances AR-mediated transactivation.[UniProtKB:P62826] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedNuclear protein import requires a precisely choreographed series of interactions between nuclear pore components and soluble factors such as importin-beta, Ran, and nuclear transport factor 2 (NTF2). We used the crystal structure of the GDPRan-NTF2 complex to design mutants in the switch II loop of Ran to probe the contribution of Lys71, Phe72 and Arg76 to this interaction. X-ray crystallography showed that the F72Y, F72W and R76E mutations did not introduce major structural changes into the mutant Ran. The GDP-bound form of the switch II mutants showed no detectable binding to NTF2, providing direct evidence that salt bridges involving Lys71 and Arg76 and burying Phe72 are all crucial for the interaction between Ran and NTF2. Nuclear protein accumulation in digitonin-permeabilzed cells was impaired with Ran mutants deficient in NTF2 binding, confirming that the NTF2-Ran interaction is required for efficient transport. We used mutants of the yeast Ran homologue Gsp1p to investigate the effect of the F72Y and R76E mutations in vivo. Although neither mutant was viable when integrated into the genome as a single copy, yeast mildly overexpressing the Gsp1p mutant corresponding Ran F72Y on a centromeric plasmid were viable, confirming that this mutant retained the essential properties of wild-type Ran. However, yeast expressing the Gsp1p mutant corresponding to R76E to comparable levels were not viable, although strains overexpressing the mutant to higher levels using an episomal 2micrometers plasmid were viable, indicating that the R76E mutation may also have interfered with other interactions made by Gsp1p. Engineered mutants in the switch II loop of Ran define the contribution made by key residues to the interaction with nuclear transport factor 2 (NTF2) and the role of this interaction in nuclear protein import.,Kent HM, Moore MS, Quimby BB, Baker AM, McCoy AJ, Murphy GA, Corbett AH, Stewart M J Mol Biol. 1999 Jun 11;289(3):565-77. PMID:10356329[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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