Human cytosolic ribosome (80S ribosome)

The human cytosolic ribosome is a massive macromolecular machine responsible for the translation of genetic information from messenger RNA (mRNA) into functional proteins (PubMed: 29123137). It is an 80S ribonucleoprotein complex consisting of two distinct subunits: the small 40S subunit, which is responsible for decoding the mRNA, and the large 60S subunit, which catalyzes peptide bond formation through its peptidyl transferase activity (UniProt: Ribosome). In clinical medicine, the ribosome is a significant target in oncology because cancer cells often upregulate ribosomal biogenesis to support rapid proliferation; for example, the drug omacetaxine mepesuccinate is FDA-approved to treat chronic myeloid leukemia by inhibiting the first step of protein elongation (FDA: Synribo). Beyond malignancy, genetic mutations in ribosomal proteins or assembly factors lead to a class of diseases known as ribosomopathies, such as Diamond-Blackfan anemia and Treacher Collins syndrome (PubMed: 21822282). The ribosome is also the target of potent biological toxins like ricin, which inactivates the 60S subunit, and it is frequently hijacked by viruses to prioritize the synthesis of viral proteins (PubMed: 25534318). Because the ribosome is essential for the survival of all healthy cells, therapeutic agents targeting it must be carefully managed due to risks of systemic toxicity and myelosuppression (StatPearls: Omacetaxine).

Inhibition of protein synthesis by blocking the aminoacyl-tRNA binding site (A-site), preventing peptide bond formation at the peptidyl transferase center, or inducing site-specific depurination of ribosomal RNA.