[What sequence must have an 8-nucleotide anticodon loop so that tRNA would not shift the reading frame?]

A model describing the interaction between the anticodon loop consisting of eight nucleotides and messenger RNA is proposed. A suggestion is made that the ability of eight nucleotide loop to recognize a four base codon and as a result to shift a reading frame, depends on the location of the sharp turn of polynucleotide chain within the anticodon loop. The turn will appear to be only immediately after U. This U fixes the position of the turn by the formation of the specific hydrogen bond and van-der-Vaals contacts, that are found in the common seven nucleotide anticodon loop. The model predicts whether a particular tRNA will be able to shift a reading frame or not. This prediction is in agreement with available experimental data.