In a clever experiment performed in 1962, a cysteine that wa…
In a clever experiment performed in 1962, a cysteine that was already attached to tRNACys was chemically converted to an alanine. These alanyl-tRNACys molecules were then added to a cell-free translation system from which the normal cysteinyl-tRNACys molecules had been removed. When the resulting protein was analyzed, it was found that alanine had been inserted at every point in the protein chain where cysteine was supposed to be. Discuss what this experiment tells you about the role of aminoacyl-tRNA synthetases during the normal translation of the genetic code (2 pts). Give an example of a posttranslational modification that might be lost when Cys is replaced by Ala and how this would affect function (2 pts).