Ran's C-terminal, Basic Patch, and Nucleotide Exchange Mechanisms in Light of a Canonical Structure for Rab, Rho, Ras, and Ran GTPases

Interactions involving H30^Ran and Ran's C-terminal switching mechanism. See text for details. (A) Ran-GTP-importin-β. Note that H30^Ran forms an aromatic-aromatic interaction with F161^Ran that is similar to the canonical interaction (Fig.4 C). Rather than simply interacting with canonical F161^Ran, however, H30^Ran inserts itself into an aromatic pocket formed by F161^Ran and two other aromatic residues specifically conserved in Ran, F26^Ran and F157^Ran (data not shown). (B) Ran-GDP. H30^Ranappears to be critical for establishing this conformation, in which Ran's C-terminal linker displaces the F35^Ran interaction with guanine. The inset provides a different perspective that shows main-chain to main-chain hydrogen bonds between the C-terminal and H30 regions.