InterPro domain: IPR000156

Ran is an evolutionary conserved member of the Ras superfamily that regulates all receptor-mediated transport between the nucleus and the cytoplasm. Ran Binding Protein 1 (RanBP1) has guanine nucleotide dissociation inhibitory activity, specific for the GTP form of Ran and also functions to stimulate Ran GTPase activating protein(GAP)-mediated GTP hydrolysis by Ran. RanBP1 contributes to maintaining the gradient of RanGTP across the nuclear envelope high (GDI activity) or the cytoplasmic levels of RanGTP low (GAP cofactor) [ 1 ].

All RanBP1 proteins contain an approx 150 amino acid residue Ran binding domain. Ran BP1 binds directly to RanGTP with high affinity.There are four sites of contact between Ran and the Ran binding domain. One of these involves binding of the C-terminal segment of Ran to a groove on the Ran binding domain that is analogous to the surface utilised in the EVH1-peptide interaction [ 2 ]. Nup358 contains four Ran binding domains. The structure of the first of these is known [ 3 ].

1. Regulation of nuclear import and export by the GTPase Ran. Int. Rev. Cytol. 217, 41-91
2. Structure of EVH1, a novel proline-rich ligand-binding module involved in cytoskeletal dynamics and neural function. Nat. Struct. Biol. 6, 661-5
3. Structure of a Ran-binding domain complexed with Ran bound to a GTP analogue: implications for nuclear transport. Nature 398, 39-46