Question

QUESTION:

"In most organisms, AUG and AUA triplets encode methionine and isoleucine, respectively. This is the only case in the standard genetic code where codons that code for two different amino acids are separated only by bases of the same type at the third position. The strategy for the assignment of AUG codons to methionine, and AUA codons to isoleucine, represents a striking case of interspecies variation (Blanquet et al., 2005, Grosjean and Bjork, 2004)."

--Jones et al. (2008). Mol Cell. 29(3):401.

c. If the anticodons are the same for both tRNAs, explain how discriminator regions might help the tRNAs find the proper codon.

Answer 1

Question

c. The descriminator site in the tRNA is recognized by specific aminoacyl tRNA synthase. The fourth nucleotide serve as important site for "discrimator" to divide tRNA into group for recognition sequence. This discriminator sequence can differentiate between AUG and AUA codon.