mitoribosomal

Mitoribosomes are the molecular machines responsible for protein synthesis within mitochondria. Unlike the larger, 80S ribosomes found in the cytoplasm of eukaryotic cells, mitoribosomes are structurally similar to the 70S ribosomes of bacteria, reflecting the endosymbiotic origin of mitochondria. These organelles are believed to have evolved from free-living bacteria that were engulfed by an ancestral eukaryotic cell.

The mitoribosome is composed of two subunits, a small subunit (30S) and a large subunit (50S), which together form the complete 70S mitoribosome. These subunits are made up of ribosomal RNA (rRNA) and a set of proteins. The specific rRNA sequences and protein components of mitoribosomes can vary significantly between different species, and even between different tissues within the same organism. This variability reflects ongoing evolutionary adaptation and functional specialization.

Mitochondria possess their own circular DNA (mtDNA) that encodes a limited number of proteins, most of which are essential components of the electron transport chain. Mitoribosomes translate these mtDNA-encoded messenger RNAs (mRNAs) into proteins. However, the majority of mitochondrial proteins are synthesized in the cytoplasm by cytosolic ribosomes and then imported into the mitochondria. The process of mitochondrial protein synthesis is crucial for cellular respiration and energy production, making mitoribosomes vital for the survival of most eukaryotic cells. Dysfunctional mitoribosomes are linked to a range of human diseases, including neurodegenerative disorders and metabolic conditions.