Transcription of Ribosomal Genes
Transcription of rRNA genes is the first step in ribosome biogenesis and therefore is crucial in the understanding of the molecular and cellular aspects of ribosome production. Moreover, a specialized cell structure—the nucleolus—is built at the site of the active rRNA genes. Here, I shall consider only some characteristics of the active rRNA genes in eukaryotes directly related to the elucidation of the molecular architecture and dynamics of the nucleolus. Although not made there, the product of the 5 S rRNA genes is integrated into preribosomes in the nucleolus. The transcription of 5 S rRNA genes is understood to considerable detail (Korn and Gurdon 1981, Brown 1982) and an analysis of the relevant data will be presented. Unfortunately, the information on the transcription of r-protein genes is still in an embryonic stage. We can only hope that our knowledge on the expression of these important “household genes” will soon be expanded. At present it is perhaps justified to think that r-protein genes are transcribed and expressed according to the general rules elucidated for many eukaryotic structural genes (see Darnell 1982).
KeywordsXenopus Laevis Ribosomal Gene Physarum Polycephalum rDNA Transcription Nonhistone Protein
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