cytosolic large ribosomal subunit

Definition

Target type: cellularcomponent

The large subunit of a ribosome located in the cytosol. [GOC:mtg_sensu]

The cytosolic large ribosomal subunit is a complex macromolecular assembly responsible for protein synthesis in the cytoplasm of eukaryotic cells. It consists of numerous proteins and ribosomal RNAs (rRNAs) organized into a highly intricate structure. The large subunit is responsible for the peptidyl transferase activity, which catalyzes the formation of peptide bonds between amino acids during protein synthesis. It also plays a role in the decoding of mRNA and the translocation of tRNA molecules during translation. The large subunit is composed of three major structural domains:
1. **The peptidyl transferase center (PTC):** Located in the central region of the large subunit, the PTC is the catalytic site for peptide bond formation. It is composed of a highly conserved region of rRNA that interacts with the 3' end of tRNA molecules and facilitates the transfer of the growing polypeptide chain from one tRNA to another.
2. **The decoding center:** Located near the PTC, the decoding center is responsible for recognizing the correct tRNA molecule based on the mRNA codon. It interacts with the anticodon loop of tRNA and ensures that the correct amino acid is incorporated into the growing polypeptide chain.
3. **The GTPase-associated center (GAC):** Located near the decoding center, the GAC is involved in the binding and hydrolysis of GTP, which provides energy for ribosome translocation. It interacts with various translation factors that regulate ribosome movement along the mRNA.
These domains are interconnected and work in concert to ensure accurate and efficient protein synthesis. The cytosolic large ribosomal subunit is a highly dynamic structure that undergoes conformational changes throughout the translation process. These changes are essential for the proper function of the ribosome and are regulated by interactions with various translation factors.
**In addition to these core structural domains, the cytosolic large ribosomal subunit contains several other functional elements:**
* **Binding sites for tRNA:** The large subunit contains binding sites for three tRNA molecules: the A site, the P site, and the E site. The A site binds the incoming aminoacyl-tRNA, the P site binds the tRNA carrying the growing polypeptide chain, and the E site binds the deacylated tRNA before it is released from the ribosome.
* **Binding site for mRNA:** The large subunit contains a binding site for mRNA, which interacts with the small ribosomal subunit to ensure accurate translation of the genetic code.
* **Binding sites for translation factors:** The large subunit contains binding sites for various translation factors, including elongation factors, termination factors, and ribosome recycling factors. These factors regulate the different stages of translation, including initiation, elongation, and termination.
**Overall, the cytosolic large ribosomal subunit is a complex and essential cellular machine that plays a central role in protein synthesis. Its intricate structure and diverse functional elements ensure accurate and efficient translation of the genetic code, which is crucial for all cellular processes.**'"

Proteins (78)

Compounds (23)