GTPase with low activity. Has higher affinity for GDP than for GTP. Plays a role in resistance to intracellular pathogens. Required for disruption of the parasitophorous vacuole formed following T.gondii infection and subsequent killing of the parasite. Mediates resistance to C.trachomatis infection by targeting bacterial inclusions to autophagosomes for subsequent lysosomal destruction. GTP + H2O = GDP + H(+) + phosphate Monomer, as apoenzyme and in the GDP-bound form. Homooligomer, upon GTP binding. Interacts with HOOK3. Localizes to the bacterial inclusions formed following C.trachomatis infection. Accumulates in a GTP-bound form on the parasitophorous vacuole membranes formed following T.gondii infection but exists in a GDP-bound form in uninfected cells. Up-regulated by IFNG, IFNA1 and lipopolysaccharide (LPS) within 20 hours. Transiently up-regulated during the early stages of infection by Listeria monocytogenes. After 6 days expression is back to basal levels. Belongs to the TRAFAC class dynamin-like GTPase superfamily. IRG family.