Fig. 8: Transit of tmRNA through the B1a, B1b, and B1c bridges during trans-translation.
From: Structures of tmRNA and SmpB as they transit through the ribosome
Close-up view of the opening and closing of bridges B1a, B1b and B1c during a pre-accommodation, b accommodation, c translocation and d intermediate translocation (TRANS*) states. The 50S ribosomal subunit is blue, 30S is khaki, elongation factor EF-Tu is pink, tmRNA is red, SmpB is purple and tRNAphe is green. The tmRNA helix H2 and the 50S helix H38 are also labelled. Black arrows indicate the degree of rotation and tilt of the 30S head measured with respect to its body, as per Nguyen and Whitford87. Orange arrows highlight the opening of bridges B1b and B1c. All maps are contoured at 2.5 σ, where sigma represents variance in the map.
