60S subunit

Component of the eukaryotic ribosome responsible for protein synthesis

Template:Infobox ribosomal subunit

The 60S ribosomal subunit is a critical component of the eukaryotic ribosome, which is responsible for protein synthesis in cells. The ribosome is a complex molecular machine found within all living cells that performs the synthesis of proteins by translating messenger RNA (mRNA) into polypeptide chains. The eukaryotic ribosome is composed of two subunits: the small 40S subunit and the large 60S subunit.

Structure

The 60S ribosomal subunit is the larger of the two subunits that make up the eukaryotic ribosome. It is composed of three types of ribosomal RNA (rRNA) molecules and approximately 49 ribosomal proteins. The rRNA components include:

• 28S rRNA: This is the largest rRNA molecule in the 60S subunit and plays a crucial role in the peptidyl transferase activity of the ribosome.
• 5.8S rRNA: This rRNA is involved in the structural stability of the ribosome and interacts with both the 28S rRNA and the 5S rRNA.
• 5S rRNA: This rRNA is important for the assembly and stability of the ribosome.

The proteins associated with the 60S subunit contribute to its structural integrity and functional capabilities. These proteins are involved in various aspects of ribosome function, including the stabilization of rRNA structures and the facilitation of interactions with other molecules during translation.

Function

The primary function of the 60S ribosomal subunit is to catalyze the formation of peptide bonds between amino acids during protein synthesis. This process occurs in the peptidyl transferase center of the ribosome, which is located within the 60S subunit. The 60S subunit also plays a role in the translocation of tRNA and mRNA during translation, ensuring that the ribosome moves along the mRNA in a coordinated manner.

The 60S subunit works in conjunction with the 40S subunit to decode the mRNA sequence and synthesize the corresponding polypeptide chain. The 40S subunit is responsible for binding the mRNA and the initiator tRNA, while the 60S subunit facilitates the elongation and termination phases of protein synthesis.

Assembly

The assembly of the 60S ribosomal subunit is a complex process that occurs in the nucleolus of the cell. It involves the transcription of rRNA genes, the processing and modification of rRNA, and the sequential addition of ribosomal proteins. The assembly process is tightly regulated and involves numerous assembly factors and chaperones that ensure the correct folding and maturation of the ribosomal subunit.

Once assembled, the 60S subunit is transported to the cytoplasm, where it joins with the 40S subunit to form a functional ribosome capable of translating mRNA into proteins.

Clinical Significance

Mutations or defects in the components of the 60S ribosomal subunit can lead to a variety of human diseases, collectively known as ribosomopathies. These conditions often result in impaired protein synthesis and can affect cell growth and proliferation. Examples of ribosomopathies include Diamond-Blackfan anemia and Shwachman-Diamond syndrome.

Also see

• Ribosome
• 40S ribosomal subunit
• Protein synthesis
• Ribosomal RNA
• Translation (biology)