Catalyzes the conversion of GTP to GDP through hydrolysis of the gamma-phosphate bond in GTP. When hydroxylated at C-3 of 'Lys-21' by JMJD7, may bind to RNA and play a role in translation. GTP + H2O = GDP + H(+) + phosphate Interacts with RWDD1; this interaction confers protection to polyubiquitination and proteolytic degradation (By similarity). Interacts with JMJD7; this interaction is direct (PubMed:29915238). Highest levels in skeletal muscle, heart and kidney. Low levels in colon, thymus, spleen, small intestine, lung and Leukocytes. Hydroxylated (with S stereochemistry) at C-3 of Lys-21 by JMJD7; this modification hinders trypsin-catalyzed proteolysis in vitro. Polyubiquitinated. Belongs to the TRAFAC class OBG-HflX-like GTPase superfamily. OBG GTPase family.