Initiation In initiation mRNA is attached to tRNA, which is attached to the specified amino acid mRNA Translation Initiation Step We'll start with initiation. During initiation, the mRNA, the tRNA, and the first amino acid all come together within the ribosome. The mRNA strand remains continuous, but the true initiation point is the start codon, AUG. Remember that the start codon is the set of three nucleotides that begins the coded sequence of a gene. Remember also that the start codon specifies the amino acid methionine. So, methionine is the name of the amino acid that is brought into the ribosome first. And how did methionine get itself to the ribosome? By attaching to the tRNA that contains the right anticodon. The anticodon for AUG is UAC. We know that because of the rules of complementary base pairing. The tRNA with the anticodon UAC will automatically match to the codon AUG, bringing the methionine along for the ride. So, there you have it - mRNA is attached to tRNA, and tRNA is attached to methionine. That's initiation.