Structure of tRNA – The Adapter Molecule of Protein Synthesis

Structure of tRNA – The Adapter Molecule of Protein Synthesis

Transfer RNA (tRNA) is a small but essential molecule that helps decode mRNA into proteins. Its structure is cleverly designed, like a 3D cloverleaf, to perform its function efficiently. Here’s a breakdown of its main parts:

1. Acceptor Arm:
• Capped with the CCA sequence (5′ → 3′).
• This is where the specific amino acid attaches, ready to be added to the growing protein chain.
2. Anticodon Arm:
• Contains the anticodon, a set of three nucleotides.
• Responsible for recognizing the complementary codon on mRNA, ensuring the correct amino acid is incorporated.
3. D Arm:
• Named after the dihydrouridine (D) residues it carries.
• Plays a role in tRNA folding and stability.
4. TψC Arm:
• Contains the sequence T – pseudouridine (ψ) – C.
• Important for ribosome recognition and proper tRNA positioning during translation.
5. Variable Arm:
• The most flexible part of tRNA.
• Based on its length, tRNAs are classified into:
• Class I tRNAs: Most common (~75%), with a short variable arm of 3–5 base pairs.
• Class II tRNAs: Less common, with a long variable arm of 13–20 base pairs.

Summary:
tRNA is like a molecular adapter, with each arm playing a unique role—attaching amino acids, reading codons, ensuring proper folding, and interacting with ribosomes. This clever design makes protein synthesis accurate and efficient.