Human 28S ribosomal RNA (28S rRNA)

The human ribosomal peptidyl transferase center (PTC) is the catalytic core of the 28S ribosomal RNA (rRNA) located within the large (60S) ribosomal subunit. It functions as a ribozyme, facilitating the formation of peptide bonds between the growing polypeptide chain and incoming amino acids during translation elongation. This catalytic activity is fundamentally independent of the specific nascent-chain sequence, relying instead on the precise positioning of tRNA substrates within the A and P sites. In clinical practice, the PTC is a validated therapeutic target; for example, Omacetaxine mepesuccinate (Synribo) inhibits protein synthesis by binding to the A-site of the PTC, thereby preventing the initial steps of protein translation in a nascent-chain-independent manner. Beyond oncology, the PTC is a target for potent toxins like ricin and Shiga toxin, which enzymatically depurinate the rRNA, leading to irreversible ribosome inactivation and cell death. Understanding the structural nuances of the human PTC is essential for developing selective inhibitors that can target the hyperactive translation machinery characteristic of malignant cells while minimizing damage to healthy tissues.

Other names

Peptidyl transferase centerPTCLarge subunit ribosomal RNA28S rRNARibosomal peptidyltransferase

Inhibition of peptide bond formation by competitive binding to the ribosomal A-site or enzymatic inactivation of the rRNA scaffold.