28S ribosomal RNA

28S Ribosomal RNA

The 28S ribosomal RNA (28S rRNA) is a component of the large subunit of eukaryotic ribosomes, which are the molecular machines responsible for protein synthesis in cells. The 28S rRNA is a crucial part of the ribosomal structure and function, playing a key role in the translation of mRNA into proteins.

Structure

The 28S rRNA is a large RNA molecule, typically around 4,700 nucleotides in length, although the exact size can vary slightly between species. It is part of the 60S large ribosomal subunit in eukaryotes, which also includes the 5S rRNA, 5.8S rRNA, and approximately 49 ribosomal proteins. The 28S rRNA forms the core of the ribosome's peptidyl transferase center, which is responsible for catalyzing the formation of peptide bonds between amino acids.

Function

The primary function of the 28S rRNA is to facilitate the assembly of amino acids into protein chains. It does this by:

• Providing a scaffold for the binding of ribosomal proteins and other rRNA molecules.
• Catalyzing the peptidyl transferase reaction, which links amino acids together.
• Ensuring the proper alignment of the mRNA and tRNA molecules during translation.

The 28S rRNA is also involved in the binding of elongation factors and other molecules that assist in the translation process.

Evolutionary Significance

The 28S rRNA is highly conserved across eukaryotic species, reflecting its essential role in protein synthesis. However, it also contains regions of variability that can be used for phylogenetic studies to determine evolutionary relationships between organisms. These variable regions are often used in molecular taxonomy and evolutionary biology.

Clinical Relevance

Mutations or alterations in the 28S rRNA can lead to defects in ribosome function, which can result in diseases known as ribosomopathies. These conditions can affect cell growth and proliferation, leading to developmental disorders and cancer.

Also see

• Ribosome
• 5S ribosomal RNA
• 5.8S ribosomal RNA
• Ribosomal RNA
• Protein synthesis
• Translation (biology)