ABSTRACT
The canonical principles of codon reading as laid down in the wobble rules, undoubtedly predict in a very useful way the probability of a certain anticodon being able to read a particular codon in the elongation of the peptide chain during protein synthesis. The initiation codons AUG, UUG, and GUG are all read by the same anticodon (CAU) indicating that the reading of the first nucleotide of the codon is relaxed and not according to the Watson-Crick pairing rules. The fact that almost all the transfer ribonucleic acids (tRNA) that read without discrimination have an unsubstituted U in the wobble position prompted the suggestion that in the pertinent organelles and organisms this nucleotide can form stable base pairs with all standard nucleotides. The synthetase function could be taken over by protein enzymes leaving the tRNA free to develop a structure that allowed greater sophistication in codon reading, including the discrimination between the nucleotides in the third codon position.
