Variation among human 28S ribosomal RNA genes.

TLDR

Human 28S rRNA shows extreme sequence and size variation, with intraspecies heterogeneity observed in a variable region cloned from six genes, reflecting broader rRNA diversity among species. The study aims to use the rapid divergence of variable ribosomal regions to estimate divergence times between closely related species. The complete 5025‑base human 28S rRNA sequence was determined, revealing intraspecies heterogeneity and interspecies divergence rates of 0.8 % in conserved regions and 3.7 % in a variable region compared to chimpanzee, suggesting species‑specific functional differences.

Abstract

We report the complete 5025-base sequence of the human 28S rRNA gene. Variability within the species has been demonstrated by sequencing a variable region from six separately cloned genes. This region is one of three large subunit rRNA regions that show extreme sequence and size variation among species. The interspecies differences suggest species-specific functions for these sections, while the intraspecies heterogeneity indicates differences among ribosomes. Comparison of the human gene with a partial sequence from the chimpanzee 28S gene yields divergence rates for the two species: 0.8% for conserved regions of the gene and 3.7% for a variable region. The rapid divergence rates of variable regions in the ribosomal gene may permit answers to the question of time of separation of closely related species.