Met-tRNAiMet

Definition

met-tRNAiMet refers to the specific transfer RNA (tRNA) molecule that carries methionine, the first amino acid incorporated into a growing polypeptide chain during protein synthesis. This tRNA plays a crucial role in initiating translation, as it recognizes the start codon on the mRNA and ensures that methionine is added to the beginning of the protein being synthesized.

5 Must Know Facts For Your Next Test

1. The presence of met-tRNAiMet at the start codon ensures that every newly synthesized protein begins with methionine, which is crucial for proper folding and function.
2. In eukaryotes, met-tRNAiMet is specifically recognized by initiation factors that help assemble the ribosomal subunits at the start site of translation.
3. The methionine residue can sometimes be removed post-translationally, allowing for functional diversity in proteins.
4. In prokaryotes, the equivalent tRNA is known as fMet-tRNAfMet, which carries formylmethionine and is used to initiate protein synthesis differently from eukaryotes.
5. The correct pairing of met-tRNAiMet with the start codon (AUG) on mRNA is essential for accurate protein synthesis and ensures the fidelity of translation.

Review Questions

• How does met-tRNAiMet contribute to the initiation phase of protein synthesis?
  • met-tRNAiMet is crucial for initiating protein synthesis as it binds to the start codon (AUG) on mRNA within the ribosome. This binding facilitates the assembly of ribosomal subunits and ensures that methionine is added first in the growing polypeptide chain. Without met-tRNAiMet, translation could not properly commence, highlighting its essential role in forming functional proteins.
• Compare and contrast met-tRNAiMet in eukaryotic and prokaryotic organisms during translation initiation.
  • In eukaryotic organisms, met-tRNAiMet carries methionine and requires various initiation factors to assist in forming the initiation complex at the ribosome. In contrast, prokaryotes use fMet-tRNAfMet, which carries formylmethionine. This difference reflects how each type of organism has adapted its translational machinery while still maintaining the fundamental goal of starting protein synthesis with a specific amino acid.
• Evaluate the impact of accurate met-tRNAiMet binding on protein synthesis fidelity and potential cellular outcomes if errors occur.
  • Accurate binding of met-tRNAiMet to the start codon is essential for maintaining fidelity in protein synthesis. If met-tRNAiMet fails to bind correctly or if incorrect tRNAs are utilized, it can lead to faulty proteins that may misfold or lose functionality. Such errors can have serious cellular consequences, including disrupted cellular processes, potentially leading to diseases or cell death. Ensuring proper initiation sets the stage for successful translation and ultimately affects organismal health.

Related terms

Aminoacyl-tRNA: Aminoacyl-tRNA is a tRNA molecule that has an amino acid attached to it, ready to deliver that amino acid to the growing polypeptide chain during translation.

Ribosome: Ribosomes are molecular machines that facilitate the translation of mRNA into proteins by providing a site for tRNAs to bring their corresponding amino acids.

Translation initiation: Translation initiation is the first stage of protein synthesis where the ribosome assembles around the start codon of the mRNA, and met-tRNAiMet binds to this start codon to begin polypeptide synthesis.