Question

Why ATG is a start codon?

Answer 1

ATG is a start codon because:

1. Methionine codons are used to start protein translation in the majority of cases.
2. The sequence is ATG in eukaryotic DNA, but AUG in RNA.
3. The start codon always codes for methionine in eukaryotes and Archaea, while it codes for N-formyl methionine in bacteria, mitochondria, and plastids (fMet).
4. AUG is the most commonly used start codon (i.e., ATG in the corresponding DNA sequence).
5. Because it codes for methionine and serves as the start codon, "AUG" is the first codon in almost all reading frames.
6. Regardless of the encoded amino acid, nearly all cells employ the same start codon.