Reading frame selection and transfer RNA anticodon loop stacking

Messenger RNA9s are translated in successive three-nucleotide steps (a reading frame), therefore decoding must proceed in only one of three possible frames. A molecular model for correct propagation of the frame is presented based on (i) the measured translational properties of transfer RNA9s (tRNA9s) that contain an extra nucleotide in the anticodon loop and (ii) a straightforward concept about anticodon loop structure. The model explains the high accuracy of reading frame maintenance by normal tRNA9s, as well as activities of all characterized frameshift suppressor tRNA9s that have altered anticodon loops.