GTPase involved in nucleocytoplasmic transport, participating both to the import and the export from the nucleus of proteins and RNAs. Switches between a cytoplasmic GDP- and a nuclear GTP-bound state by nucleotide exchange and GTP hydrolysis. Nuclear import receptors such as importin beta bind their substrates only in the absence of GTP-bound RAN and release them upon direct interaction with GTP-bound RAN, while export receptors behave in the opposite way. Thereby, RAN controls cargo loading and release by transport receptors in the proper compartment and ensures the directionality of the transport. Interaction with RANBP1 induces a conformation change in the complex formed by XPO1 and RAN that triggers the release of the nuclear export signal of cargo proteins. RAN (GTP-bound form) triggers microtubule assembly at mitotic chromosomes and is required for normal mitotic spindle assembly and chromosome segregation. Required for normal progress through mitosis. GTP + H2O = GDP + H(+) + phosphate Mg(2+) interacts primarily with the phosphate groups of the bound guanine nucleotide. Monomer. Interacts with rangap1, which promotes ran-mediated GTP hydrolysis. Interacts with kpnb1. Interaction with kpnb1 inhibits rangap1-mediated stimulation of GTPase activity. Interacts with rcc1 which promotes the exchange of ran-bound GDP by GTP. Interaction with kpnb1 inhibits rcc1-mediated exchange of ran-bound GDP by GTP. Interacts (GTP-bound form) with tnpo1; the interaction is direct. Interacts (GTP-bound form) with tnpo3; the interaction is direct. Interacts with kpnb1 and with tnpo1; both inhibit ran GTPase activity. Interacts (via C-terminus) with ranbp1, which alleviates the inhibition of ran GTPase activity. Interacts with rangrf, which promotes the release of bound guanine nucleotide. Rangrf and rcc1 compete for an overlapping binding site on ran. Identified in a complex with kpna2 and cse1l; interaction with ranbp1 mediates dissociation of ran from this complex. Interaction with both ranbp1 and kpna2 promotes dissociation of the complex between ran and kpnb1. Identified in a complex composed of ran, rangap1 and ranbp1. Identified in a complex that contains tnpo1, ran and ranbp1. Identified in a nuclear export complex with xpo1. Interaction with ranbp1 or ranbp2 induces a conformation change in the complex formed by xpo1 and ran that triggers the release of the nuclear export signal of cargo proteins. Component of a nuclear export receptor complex composed of kpnb1, ran, snupn and xpo1 (By similarity). Predominantly nuclear during interphase. Becomes dispersed throughout the cytoplasm during mitosis (By similarity). Ubiquitous, with the highest expression in ovary, muscle, eye and brain. Expression is low at 2 hpf and starts to increase steadily after 12 hpf to reach adult levels at 72 hpf. Belongs to the small GTPase superfamily. Ran family.