Which of the following codons is recognized as the START codon in protein synthesis?

The START codon in protein synthesis is recognized as AUG. This specific codon is essential because it not only signals the beginning of translation but also codes for the amino acid methionine. When ribosomes begin the process of assembling proteins, they identify the AUG codon as the point to start reading the mRNA sequence and synthesizing the corresponding polypeptide chain. Methionine is also the first amino acid incorporated into a nascent polypeptide during translation, establishing the initial sequence for protein formation. This definition and function set AUG apart from the other codons presented, which either signal stop (UAA and UAG) or code for a different amino acid (AAA).