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. Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family. BipA subfamily. Truncated N-terminus.