Aminoacyl tRNA

Aminoacyl tRNA (also known as charged tRNA or complexed tRNA) is a crucial molecule in the process of protein synthesis within the cell. It is formed when an amino acid is attached to its corresponding transfer RNA (tRNA) by a specific enzyme called aminoacyl-tRNA synthetase. This process is essential for the translation of genetic information from mRNA into a specific protein sequence, a fundamental aspect of cellular biology.

Formation

The formation of aminoacyl tRNA is a two-step process:

1. An amino acid is activated by the attachment of adenosine triphosphate (ATP), forming an aminoacyl-AMP intermediate.
2. The activated amino acid is then transferred to the tRNA molecule, specifically to the 3' end of the tRNA, resulting in the charged or aminoacyl tRNA.

This reaction is catalyzed by the enzyme aminoacyl-tRNA synthetase. There are 20 different aminoacyl-tRNA synthetases, one for each amino acid, ensuring the correct amino acid is attached to its corresponding tRNA.

Function

Aminoacyl tRNA plays a pivotal role in the translation process. During translation, the ribosome moves along the mRNA molecule, reading its nucleotide sequence in sets of three nucleotides known as codons. Each codon specifies a particular amino acid. The aminoacyl tRNA, with its attached amino acid, is then brought to the ribosome by elongation factor proteins. The anticodon loop of the tRNA pairs with the complementary codon on the mRNA, allowing the ribosome to catalyze the formation of a peptide bond between the amino acid of the tRNA in the P site and the amino acid of the incoming tRNA in the A site. This process repeats, elongating the growing polypeptide chain until a stop codon is reached, signaling the end of protein synthesis.

Significance

The accuracy of aminoacyl tRNA formation is critical for the fidelity of protein synthesis. Misacylation, where the wrong amino acid is attached to a tRNA, can lead to the production of dysfunctional proteins, which can have detrimental effects on cell function and viability. The specificity of aminoacyl-tRNA synthetases plays a crucial role in ensuring the accuracy of protein synthesis.

See Also

• Protein synthesis
• Ribosome
• Transfer RNA
• Genetic code