1a2k

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spinqualitylabelsall models 1a2k, resolution 2.5Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

GDPRAN-NTF2 COMPLEX

Overview

Nuclear transport factor 2 (NTF2) and the Ras-family GTPase Ran are two, soluble components of the nuclear protein import machinery. NTF2 binds, GDP-Ran selectively and this interaction is important for efficient, nuclear protein import in vivo. We have used X-ray crystallography to, determine the structure of the macromolecular complex formed between, GDP-Ran and nuclear transport factor 2 (NTF2) at 2.5 A resolution. The, interaction interface involves primarily the putative switch II loop of, Ran (residues 65 to 78) and the hydrophobic cavity and surrounding surface, of NTF2. The major contribution to the interaction made by the switch II, loop accounts for the ability of NTF2 to discriminate between GDP and, GTP-bound forms of Ran. The aromatic side-chain of Ran Phe72 inserts into, the NTF2 cavity and accounts for 22% of the surface area buried by the, interaction interface, while salt bridges are formed between Lys71 and, Arg76 of Ran with Asp92/Asp94 and Glu42 of NTF2, respectively. These salt, bridges account for the inhibition of the Ran-NTF2 interaction by NTF2, mutants such as E42 K and D92/94N in which the negatively charged residues, surrounding the cavity were altered. Because the interaction interface, maintains the positions of key Ran residues involved in binding MgGDP, NTF2 binding may help stabilize the switch state of Ran, possibly in the, context of targeting it to other components of the nuclear protein import, machinery to specify directionality of transport. The binding of GDP-Ran, at the NTF2 cavity raises the possibility that this interaction might be, modulated by a metabolite or small molecule substrate for NTF2's putative, enzymatic activity.

About this Structure

1A2K is a Protein complex structure of sequences from Canis lupus familiaris and Rattus norvegicus with MG, SO4 and GDP as ligands. Full crystallographic information is available from OCA.

Reference

Structural basis for molecular recognition between nuclear transport factor 2 (NTF2) and the GDP-bound form of the Ras-family GTPase Ran., Stewart M, Kent HM, McCoy AJ, J Mol Biol. 1998 Apr 3;277(3):635-46. PMID:9533885

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