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 (By similarity). Polyubiquitinated. Hydroxylated (with S stereochemistry) at C-3 of Lys-21 by JMJD7. Belongs to the TRAFAC class OBG-HflX-like GTPase superfamily. OBG GTPase family.