Effect of ribosomal protein L12 upon initiation factor IF-2 activities

The effect of removal of the 50S subunit proteins L7 and L12 upon initiation factor IF-2 activities is investigated. Both “coupled” and “non-coupled” GTPase activities are greatly reduced as is fMet-tRNA ribosomal binding. These activities can be restored by re-addition of L12. IF-2 activities are less affected by lack of L12 than EF-G dependent GTP hydrolysis. It is proposed that ribosomal sites for initiation factor and elongation factor -dependent GTP hydrolysis are closely associated.