Primary Citation of Related Structures:   1RRP
PubMed Abstract: 
The protein Ran is a small GTP-binding protein that binds to two types of effector inside the cell: Ran-binding proteins, which have a role in terminating export processes from the nucleus to the cytoplasm, and importin-beta-like molecules that bind cargo proteins during nuclear transport ...
The protein Ran is a small GTP-binding protein that binds to two types of effector inside the cell: Ran-binding proteins, which have a role in terminating export processes from the nucleus to the cytoplasm, and importin-beta-like molecules that bind cargo proteins during nuclear transport. The Ran-binding domain is a conserved sequence motif found in several proteins that participate in these transport processes. The Ran-binding protein RanBP2 contains four of these domains and constitutes a large part of the cytoplasmic fibrils that extend from the nuclear-pore complex. The structure of Ran bound to a non-hydrolysable GTP analogue (Ran x GppNHp) in complex with the first Ran-binding domain (RanBD1) of human RanBP2 reveals not only that RanBD1 has a pleckstrin-homology domain fold, but also that the switch-I region of Ran x GppNHp resembles the canonical Ras GppNHp structure and that the carboxy terminus of Ran is wrapped around RanBD1, contacting a basic patch on RanBD1 through its acidic end. This molecular 'embrace' enables RanBDs to sequester the Ran carboxy terminus, triggering the dissociation of Ran x GTP from importin-beta-related transport factors and facilitating GTP hydrolysis by the GTPase-activating protein ranGAP. Such a mechanism represents a new type of switch mechanism and regulatory protein-protein interaction for a Ras-related protein.
Related Citations: 
Ranbp1 is Crucial for the Release of Rangtp from Importin Beta-Related Nuclear Transport Factors Bischoff, F.R., Gorlich, D. (1997) FEBS Lett 419: 249
Dynamic and Equilibrium Studies on the Interaction of Ran with its Effector, Ranbp1 Kuhlmann, J., Macara, I., Wittinghofer, A. (1997) Biochemistry 36: 12027
A Ran-Binding Motif Found in Nuclear Pore Proteins Hartmann, E., Gorlich, D. (1995) Trends Cell Biol 5: 192
A Giant Nucleopore Protein that Binds Ran/Tc4 Yokoyama, N., Hayashi, N., Seki, T., Pante, N., Ohba, T., Nishii, K., Kuma, K., Hayashida, T., Miyata, T., Aebi, U., Fukui, M., Nishimoto, T. (1995) Nature 376: 184
The C Terminus of the Nuclear Ran/Tc4 Gtpase Stabilizes the Gdp-Bound State and Mediates Interactions with Rcc1, Ran-Gap, and Htf9A/Ranbp1 Richards, S.A., Lounsbury, K.M., Macara, I.G. (1995) J Biol Chem 270: 14405
Co-Activation of Rangtpase and Inhibition of GTP Dissociation by Ran-GTP Binding Protein Ranbp1 Bischoff, F.R., Krebber, H., Smirnova, E., Dong, W., Ponstingl, H. (1995) EMBO J 14: 705
Organizational Affiliation: 
Abteilung Strukturelle Biologie, Max-Planck-Institut für molekulare Physiologie, Dortmund, Germany.