Initiator tRNA

Definition

Initiator tRNA (transfer RNA) is a specialized tRNA molecule that is responsible for recognizing the start codon (AUG) on mRNA and initiating protein synthesis. It carries the amino acid methionine in eukaryotes or a formylated methionine (fMet) in prokaryotes.

5 Must Know Facts For Your Next Test

1. Initiator tRNA binds to the small ribosomal subunit along with other initiation factors to form the initiation complex.
2. It specifically recognizes and pairs with the start codon AUG on the mRNA strand.
3. In eukaryotic cells, initiator tRNA carries methionine, whereas in prokaryotic cells, it carries formylmethionine (fMet).
4. The unique structure of initiator tRNA prevents it from being added to the growing peptide chain at internal positions during elongation.
5. Mutations or malfunctions in initiator tRNA can lead to errors in protein synthesis, impacting cellular function and health.

Review Questions

Related terms

Ribosome: A molecular machine made of rRNA and proteins that facilitates translation by assembling amino acids into polypeptide chains.

Start Codon:

A specific sequence of three nucleotides (AUG) on mRNA that signals the beginning of translation.

Methionine: An essential amino acid carried by initiator tRNA in eukaryotes, starting the process of protein synthesis.