Genes that are transcribed into 5S rRNAs. Such genes occur in tandemly linked clusters in all eukaryotes. In Xenopus laevis, 5S rRNA genes account for 0.5% of the entire genome. There are three separate 5S rRNA multigene families. Two of these, the major oocyte and trace oocyte families, are expressed only in oocytes, while a third, somatic 5S rDNA, is expressed in all types of somatic cells. The major oocyte, trace oocyte, and somatic 5S rDNAs are present in 20,000, 1,300, and 400 copies, respectively, per haploid genome.
Subjects: Genetics and Genomics.