Variation among human 28S ribosomal RNA genes

Area of Science:

• Genetics
• Molecular Biology
• Evolutionary Biology

Background:

• Ribosomal RNA (rRNA) genes are crucial for protein synthesis.
• The 28S rRNA gene, a component of the large ribosomal subunit, exhibits variability across species.
• Understanding this variability can provide insights into evolutionary relationships.

Purpose of the Study:

• To determine the complete sequence of the human 28S rRNA gene.
• To investigate sequence and size variability within the human 28S rRNA gene.
• To compare human and chimpanzee 28S rRNA gene sequences to estimate divergence rates.

Main Methods:

• Sequencing of the complete 5025-base human 28S rRNA gene.
• Sequencing of a variable region from six separately cloned human genes.
• Comparative sequence analysis between human and chimpanzee 28S rRNA genes.

Main Results:

• The complete sequence of the human 28S rRNA gene was determined.
• Significant sequence and size variability were observed within the human 28S rRNA gene, particularly in specific regions.
• Human and chimpanzee 28S rRNA genes showed divergence rates of 0.8% in conserved regions and 3.7% in variable regions.

Conclusions:

• The human 28S rRNA gene sequence has been fully elucidated.
• Intraspecies heterogeneity in 28S rRNA suggests functional differences among ribosomes.
• Rapid divergence rates in variable regions of the 28S rRNA gene can aid in determining the evolutionary separation of species.