A 50S ribosomal subunit assembly protein with GTPase activity, required for 50S subunit assembly at low temperatures, may also play a role in translation. Binds GTP and analogs. Binds the 70S ribosome between the 30S and 50S subunits, in a similar position as ribosome-bound EF-G; it contacts a number of ribosomal proteins, both rRNAs and the A-site tRNA. GTP + H2O = GDP + H(+) + phosphate Monomer. Binds to ribosomes. 3-fold induction by growth at 15 degrees Celsius. No visible growth phenotype at 15 degrees Celsius. Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family. BipA subfamily.