File:Ecoli 70S ribosome pair with tRNA mRNA.png

English: Two E coli 70S ribosomes, as they occur in the crystal repeating unit of PDB entries 3R8N, 3R8O, 3R8S, and 3R8T. 30S subunits are near the center (in blue and yellow, with RNA lighter and proteins darker); tRNA and mRNA (red) are in the subunit interfaces; 50S subunits are toward the outside (in green and pink). The lefthand ribosome is in the fully ratcheted conformational state, with an RRF release factor bound, and the righthand ribosome is in the resting, unratcheted state. Nonequivalence of the two ribosomes can be seen by comparing the green protein that sticks out from its 50S and binds to the opposite 30S (yellow) versus the equivalent protein (red, top right) that is nowhere near its opposite 30S and instead binds to the RNA of its own 50S subunit (pale pink). Dunkle et al. 2011, Science 332:981.