Putative GTPase which is required for IFNG-mediated clearance of acute protozoan and bacterial infections. Functions in innate immune response probably through regulation of autophagy. May regulate pro-inflammatory cytokine production and prevent endotoxemia upon infection. Required for macrophage motility and possibly also for adhesion. Behaves like an integral membrane protein. Recruited to the plasma membrane around forming phagocytic cups, it remains associated with maturing phagosomes. Association with phagosomes is dependent on nucleotide-binding but is IFNG-independent. Preferentially associated with cis- and medial-Golgi. Also detected in late endosomes and lysosomes. Expressed in lung and primary macrophages. Up-regulated by LPS and IFNG (at protein level). Up-regulated upon infection by various pathogens including T.cruzi, T.gondii, L.monocytogenes, M.tuberculosis and murine cytomegalovirus. Mice do not show obvious abnormalities except a loss of resistance to infection by S.typhimurium, T.cruzi, T.gondii, L.monocytogenes and M.tuberculosis. Upon infection, alterations of blood elements occur including lymphopenia, anemia, and thrombocytopenia. Belongs to the TRAFAC class dynamin-like GTPase superfamily. IRG family.