mitochondrial ribosome

Definition

Target type: cellularcomponent

A ribosome found in the mitochondrion of a eukaryotic cell; contains a characteristic set of proteins distinct from those of cytosolic ribosomes. [GOC:mah, ISBN:0198506732]

The mitochondrial ribosome (mitoribosome) is a specialized organelle found within the mitochondria of eukaryotic cells. It is responsible for the synthesis of proteins essential for mitochondrial function, including those involved in oxidative phosphorylation and the electron transport chain. The mitoribosome consists of two subunits: the small subunit (SSU) and the large subunit (LSU).

The SSU, also known as the 39S subunit in mammals, is composed of a single ribosomal RNA molecule (rRNA) and approximately 30 ribosomal proteins (r-proteins). The rRNA molecule, known as 12S rRNA, is responsible for binding to messenger RNA (mRNA) and guiding the translation process. The r-proteins provide structural support and facilitate the binding of other molecules involved in translation.

The LSU, known as the 51S subunit in mammals, is composed of two rRNA molecules (16S rRNA and 21S rRNA) and approximately 50 r-proteins. The 16S rRNA molecule plays a critical role in peptide bond formation, while the 21S rRNA molecule is involved in mRNA decoding. The r-proteins within the LSU are responsible for maintaining the structural integrity of the subunit and facilitating the interactions between the rRNA molecules and other components of the translation machinery.

The mitoribosome exhibits several key differences compared to the cytoplasmic ribosome, including:

1. **Distinct rRNA sequences:** The rRNA molecules in the mitoribosome have unique sequences that are distinct from those found in cytoplasmic ribosomes.
2. **Specific r-proteins:** The mitoribosome contains a set of r-proteins that are specific to mitochondria and are not found in cytoplasmic ribosomes.
3. **Unique structure:** The overall structure of the mitoribosome differs from that of the cytoplasmic ribosome, with variations in the arrangement of rRNA molecules and r-proteins.

The mitoribosome is a highly dynamic structure that undergoes complex rearrangements during the translation process. It interacts with a variety of molecules, including tRNAs, mRNAs, and translation factors, to ensure accurate protein synthesis. The proper functioning of the mitoribosome is essential for mitochondrial respiration and energy production, making it a critical component of cellular metabolism.'
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Proteins (1)

Compounds (2)