tRNAs play central roles in protein synthesis by transfer amino acids to ribosome.Nucleotides in tRNA are often post-transcriptionally modified,especially residues from the anti-codon region.Position 34 is the wobble site in the anti-codon of tRNA,which is usually highly modified.Modifications at wobble nucleotide are essential to the precise recognition of anti-codon on tRNA to codon on mRNA.and lack of these modifications can cause some severe cellular deficiency in vivo.