Biochemistry · Topic
Transfer RNA (tRNA) !
tRNA is the adaptor of translation: it carries an amino acid at one end and, at the other, an anticodon that reads the mRNA codon.
Updated 2026-11-01
Key facts
- About 75–90 nucleotides; a cloverleaf in 2D and an 'L' shape in 3D.
- 3' CCA end: the amino acid attaches there (ester bond). The anticodon sits in the opposite loop.
- Transcribed by RNA polymerase III, with many modified bases (pseudouridine, dihydrouridine, inosine).
- Each aminoacyl-tRNA synthetase loads its amino acid onto the right tRNA using ATP and corrects mistakes (editing).
- Wobble at the 1st anticodon base lets one tRNA read several codons.
In detail
- Arms: acceptor (CCA), D (dihydrouridine), anticodon, variable and TΨC (binds the ribosome).
- The anticodon pairs antiparallel with the codon: anticodon 5'-CAU-3' reads codon 5'-AUG-3'.
- Inosine at the wobble position can pair with U, C or A.
- The initiator tRNA differs from the one carrying methionine inside the protein; in bacteria it carries formyl-methionine.
- Mitochondria have their own 22 tRNAs encoded by mitochondrial DNA.
- Also called
- tRNA
Clinical notes
- Mutations in the mitochondrial leucine tRNA (MT-TL1, mostly m.3243A>G) cause MELAS; in the lysine tRNA (MT-TK), MERRF.
- Mupirocin, a topical antibiotic, inhibits bacterial isoleucyl-tRNA synthetase.
Related conditions
Related
- Translation and the genetic code
- Ribosome (and the antibiotics that target it)
- RNA polymerases I, II and III
- RNA processing (cap, poly-A tail and splicing)
Test yourself
Think of the answer, then tap the question to see it.
At which end of the tRNA does the amino acid attach?
At the 3' end, to the adenosine of the CCA sequence, by an ester bond.
Which enzyme makes sure each tRNA carries the right amino acid?
The specific aminoacyl-tRNA synthetase, which also checks and corrects mistakes.
What does wobble allow?
The first anticodon base pairs loosely with the third codon base, so one tRNA can read several codons.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Transfer RNA (tRNA) (National Human Genome Research Institute (NHGRI), 2026); tRNA Aminoacylation (Reactome, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).
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Representative model, for educational purposes only.