RESUMO
Four protein factors, belonging to the GTPase superfamily, participate in bacterial biosynthesis: IF2, EF-G, EF-Tu and RF3. The exact role and mechanism of action of these proteins was of particular interest over the last several decades. Recent advances in structural methods of ribosomal research, especially application of cryoelectron microscopy, provided powerful experimental tools for the investigation of ribosomal dynamics during translation. Simultaneously, progress in the biochemical investigation of translation allowed us to link structural rearrangements occurring in the ribosome to functional changes in the ribosome-bound translational GTPases--GDP/GTP exchange, GTPase activation and its conformational changes. Accumulated data have lead to formulation of current models of mechanisms of translation. More and more facts testify in favor of the idea that the ribosome plays a prominent role both in the nucleotide exchange and in GTPase activation, thus playing the role both of GAP and GEF for RF3, IF2 and EF-G. In our work we attempted to systematize the most important experimental findings and models for mechanisms of GTPases function and regulation in prokaryotic translation.