Activation of Ran GTPase by a Legionella Effector Promotes Microtubule Polymerization, Pathogen Vacuole Motility and Infection
Ran is an abundant Ras-like GTPase that was initially characterized for its role in modulating the nucleo-cytoplasmic transport of macromolecules across the nuclear envelope (NE). However, it is also critical for other cellular processes, including mitotic spindle assembly and post-mitotic nuclear envelope assembly. Several excellent reviews detail its role in these diverse processes (Gruss and Vernos, 2004; Harel and Forbes, 2004; Hetzer et al., 2002; Macara, 2001). Here, I attempt to give an overview of Ran’s functions and reconcile these with the possibility that a common molecular mechanism underlies them. Current models for how Ran modulates different cellular processes center on the biochemical concept that activation factors exist in inhibitory complexes with transport receptors (e.g. importin ), which are relieved and activated by RanGTP in a spatiotemporal manner.