60S ribosomal subunit aminoacyl-tRNA binding site (60S A-site)

The 60S ribosomal subunit aminoacyl-tRNA binding site (A-site) is a critical functional domain within the large subunit of the eukaryotic 80S ribosome (Ben-Shem et al., 2011). It is responsible for accommodating the 3-acceptor stem of the incoming aminoacyl-tRNA, positioning the amino acid in close proximity to the Peptidyl Transferase Center (PTC) for peptide bond formation (Noller, 2005). This site is a major target for various potent translation inhibitors and ribosome-inactivating proteins (RIPs). For example, the antibiotic anisomycin binds specifically to the 60S A-site, effectively blocking the elongation phase of protein synthesis (Grollman, 1967). Furthermore, the Sarcin-Ricin Loop (SRL) within the 60S A-site region is the target of lethal toxins like ricin, which enzymatically inactivates the ribosome by depurinating a conserved adenine residue (Endo et al., 1987). While its high conservation across eukaryotic cells makes it a challenging target for systemic drug development due to toxicity, it remains a significant focus in research and the development of targeted immunotoxins for cancer therapy (Garreau de Loubresse et al., 2014). The site structural integrity is essential for the binding of elongation factors such as eEF1A and eEF2, which facilitate tRNA delivery and translocation. Disruption of this site leads to immediate cessation of protein production and subsequent cellular apoptosis. Understanding the molecular architecture of the 60S A-site has been pivotal in the design of novel antimicrobial and anticancer agents that exploit subtle differences between species.

Other names

Large ribosomal subunit A-site60S A-siteRibosomal A-site (60S)Acceptor site of the 60S subunit

Inhibition of protein synthesis by binding to the 60S A-site, thereby preventing the proper positioning of aminoacyl-tRNA or the binding of elongation factors (Grollman, 1967; Endo et al., 1987).