Role of modified nucleosides in transfer ribonucleic acid. Effect of removal of the modified base adjacent to 3' end of the anticodon in codon-anticodon interaction.

Removal of base Y adjacent to the anticodon of yeast phenylalanine tRNA changes the coding properties of tRNAPhe. Phenylalanine tRNA from which base Y has been removed (tRNA:b,“) recognizes UUC better than WU. Codon UUU is read efficiently at higher Mg++ concentration or in the presence of streptomycin. A dipeptide cannot be synthesized with N-acetyl-Phe-tRNAPh” and Phe-tRNA% unless the base Y is also removed from the acetylated PhetRNA. Removal of base Y from the anticodon loop does not affect the ability of phenylalanyl-tRNA?h to form the ternary complex with GTP and the bacterial elongation factor T.