Crystal structure of human RanGDP-Nup153ZnF34 complex
[RAN_HUMAN] GTP-binding protein involved in nucleocytoplasmic transport. Required for the import of protein into the nucleus and also for RNA export. Involved in chromatin condensation and control of cell cycle (By similarity). 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. Transactivation decreases as the poly-Gln length within AR increases.    [NU153_RAT] Possible DNA-binding subunit of the nuclear pore complex (NPC). The repeat-containing domain may be involved in anchoring components of the pore complex to the pore membrane.
Publication Abstract from PubMed
The nuclear pore complex (NPC) resides in circular openings within the nuclear envelope and serves as the sole conduit to facilitate nucleocytoplasmic transport in eukaryotes. The asymmetric distribution of the small G protein Ran across the nuclear envelope regulates directionality of protein transport. Ran interacts with the NPC of metazoa via two asymmetrically localized components, Nup153 at the nuclear face and Nup358 at the cytoplasmic face. Both nucleoporins contain a stretch of distinct, Ran-binding zinc finger domains. Here, we present six crystal structures of Nup153-zinc fingers in complex with Ran and a 1.48 A crystal structure of RanGDP. Crystal engineering allowed us to obtain well diffracting crystals so that all ZnF-Ran complex structures are refined to high resolution. Each of the four zinc finger modules of Nup153 binds one Ran molecule in apparently non-allosteric fashion. The affinity is measurably higher for RanGDP than for RanGTP and varies modestly between the individual zinc fingers. By microcalorimetric and mutational analysis, we determined that one specific hydrogen bond accounts for most of the differences in the binding affinity of individual zinc fingers. Genomic analysis reveals that only in animals do NPCs contain Ran-binding zinc fingers. We speculate that these organisms evolved a mechanism to maintain a high local concentration of Ran at the vicinity of the NPC, using this zinc finger domain as a sink.
Crystallographic and biochemical analysis of the Ran-binding zinc finger domain.,Partridge JR, Schwartz TU J Mol Biol. 2009 Aug 14;391(2):375-89. Epub 2009 Jun 6. PMID:19505478
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.