What Is an Anticodon?

Anti-codons are three adjacent bases located in the middle of the tRNA anti-codon loop that can base pair with triplet codons in mRNA. In protein synthesis, it plays the role of reading the code and introducing specific amino acids into the synthesis site. ^[1]

Anti-codon

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Anti-codons are three adjacent bases located in the middle of the tRNA anti-codon loop that can base pair with triplet codons in mRNA. In protein synthesis, it plays the role of reading the code and introducing specific amino acids into the synthesis site. ^[1]

Anticodon: The RNA strand is folded and looks like a leaf shape of a clover. One end is a site carrying amino acids and the other end has 3 bases. These three bases of each tRNA (transfer RNA) can be complementary paired with the codons on the mRNA, so they are called anti-codons. Three adjacent nucleotides in the middle of the anti-codon loop of the secondary structure of a tRNA molecule constitute an anti-codon. They are complementary to the nucleotides (codons) in the mRNA bound to the ribosome based on the principle of base pairing, so during protein synthesis, the tRNA carrying a specific amino acid recognizes the code on the mRNA with its own anti-codon. , The amino acid carried is incorporated into a certain position of the polypeptide chain.

Chinese name

Anti-codon

Foreign name

anticodon

lie in

tRNA anti-codon loop

To source

biology

Anti-codon

In addition to the four common bases in anticodon, hypoxanthine (I) appears. It can read the information on mRNA to the maximum extent and reduce the error caused by mutation. So there are actually less than 61 anti-codons.

The sequence of the three nucleotides in the anti-codon loop of the transfer RNA is bound to the special code of the messenger RNA through complementary base pairing in protein synthesis.

It is known that a tRNA can only carry one amino acid, which indicates that the codon and anti-codon pairing is still very strict. But how can the anti-codon of a tRNA establish a structural relationship with its corresponding amino acid? Aminoacyl-tRNA synthetase (aaRS) builds a bridge between the amino acid carried on the amino acid arm of tRNA and the anti-codon. The enzyme has good space expansion ability and flexibility. Generally, aaRS includes at least one catalytic central domain (CCD) and one anticodon-binding domain (ABD). The amino acid of the tRNA accepts the stem (ie, the 3'-terminal CCA-OH), and is catalyzed by aaRS to bind to the amino acid activated by ATP through an ester bond. All tRNAs that carry the same amino acid (also known as iso-tRNAs) are catalyzed by the same aaRS, and each enzyme recognizes isotactic tRNAs through several special bases. It is known that aaRS binds extensively to the inner side of t-RNAs that are L-shaped.

Crystal structure of tryptophan tRNA synthetase