GTPase involved in the biogenesis of the 60S ribosomal subunit and translational activation of ribosomes. Together with sdo1, may trigger the GTP-dependent release of tif6 from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly and facilitating tif6 recycling to the nucleus, where it is required for 60S rRNA processing and nuclear export. Inhibits GTPase activity of ribosome-bound EF-2 (By similarity). GTP + H2O = GDP + H(+) + phosphate GTPase activity is stimulated in the presence of 60S subunits. Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family.