- Peptide binding site (P site): The P site is responsible for holding the growing polypeptide chain. During translation, the transfer RNA (tRNA) molecule carrying the growing polypeptide chain is bound to the P site.
- Aminoacyl (A) site: The A site is located next to the P site and is where the incoming tRNA molecule carrying a new amino acid binds. tRNA molecules first bind to the A site where their anticodon matches the three-nucleotide sequence of the codon in the mRNA.
- Exit (E) site: The E site is positioned near the A and P sites, and it provides an exit point for tRNA molecules that have delivered their amino acid to the growing polypeptide chain. After release factors bind, releasing the polypeptide chain, deacylated tRNA leaves through the E site.
- Peptidyl transferase centre: Located near the P and A sites, the peptidyl transferase centre is responsible for catalysing the formation of peptide bonds between the amino acid attached to the tRNA in the A site and the amino acid on the tRNA in the P site.
In addition to these tRNA binding sites, the large ribosomal subunit contains binding sites for various translation factors involved in protein synthesis, such as elongation factors, release factors, and GTPases, which play crucial roles in facilitating different steps of the translation process.
