Codon-anticodon pairing. A model for interacting codon-anticodon duplexes located at the ribosomal A- and P-sites.

The interaction between two codon-anticodon duplexes of the ribosomal A- and P-site-bound tRNAs is the key feature of the proposed model. This interaction prohibits non-canonical base pairing at the first and second positions of the codon and controls base pairing at the third position (wobbling rules ensuing from the model are in good accord with those generated from experiments). The model is capable of predicting codon context effects. It follows from the model that modifications of the first anticodon residue of the P-site tRNA can affect the stability of the A-site duplex, and that the translation of a DNA single chain analogue of mRNA should be accompanied by non-canonical base pairing at all three positions of the codon. These predictions of the model can be subjected to experimental tests.