28S ribosomal RNA peptidyl transferase center (28S rRNA PTC)

The 28S ribosomal RNA peptidyl transferase center (PTC) is the catalytic core of the eukaryotic 60S ribosomal subunit, functioning as a ribozyme to facilitate the formation of peptide bonds during translation (Polacek & Mankin, 2005). Located within the large subunit, the PTC ensures the correct positioning of aminoacyl-tRNA and peptidyl-tRNA to allow the nascent polypeptide chain to grow (Schmeing et al., 2005). This site is a major target for various potent Ribosome-Inactivating Proteins (RIPs), such as ricin and Shiga toxins, which specifically depurinate a conserved adenine residue in the nearby sarcin/ricin loop, effectively halting protein synthesis and leading to cell death (Endo & Tsurugi, 1987). In clinical research, the PTC is exploited through the use of immunotoxins, where toxins targeting the 28S rRNA are linked to antibodies for selective destruction of cancer cells (Grela et al., 2019). Additionally, small molecules like anisomycin and cycloheximide interact with the PTC to inhibit translation, serving as valuable tools in molecular biology and potential leads for therapeutic development. Due to its essential role in all eukaryotic cells, therapeutic strategies involving the PTC require high precision to avoid significant systemic toxicity and damage to healthy tissues.

Other names

Peptidyl transferase centerPTC60S ribosomal subunit catalytic centerLarge ribosomal subunit peptidyl transferase center

Inhibition of peptide bond formation by blocking the A-site or P-site, or through site-specific depurination of the sarcin/ricin loop which prevents elongation factor binding (Endo & Tsurugi, 1987; Polacek & Mankin, 2005).