<p>This entry describes a universal, mostly one-gene-per-genome GTP-binding protein that associates with ribosomal subunits and appears to play a role in ribosomal RNA maturation. Mutations in this gene are pleiotropic, but it appears that effects on cellular functions such as chromosome partition may be secondary to the effect on ribosome structure.</p><p>This is an essential GTPase which binds GTP, GDP and ppGpp with moderate affinity (with a twofold preference for GDP over GTP); shows high guanine nucleotide exchange rate constants for both nucleotides, and has a relatively low GTP hydrolysis rate. Deletion of the N terminus makes a protein that is non-functional in vivo but which retains nucleotide binding and GTPase activity. Required for cell cycle progression from G1 to S phase and for DNA replication [<cite idref="PUB00034535"/>].</p>