A sequence contains a lot of information such as N-terminus and C-terminus. The mRNA is interpreted by the cell by interpreting this codon. H. Group of 3 nucleotides. Four RNA nucleotides can inhibit three possible combinations. Of the 64 codon groups, 62 define amino acids, and the remaining 3 (UAA, UAG, or UGA) act as stop signals. This group represents the end of protein synthesis. There is another AUG codon with a unique function. This serves as a starting signal for initiating translation.