Ribosomal chromatin organizationThis paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.

Abstract

Mammalian cells contain approximately 400 copies of the ribosomal RNA genes organized as tandem, head-to-tail repeats spread among 6–8 chromosomes. Only a subset of the genes is transcribed at any given time. Experimental evidence suggests that, in a specific cell type, only a fraction of the genes exists in a conformation that can be transcribed. An increasing body of study indicates that eukaryotic ribosomal RNA genes exist in either a heterochromatic nucleosomal state or in open euchromatic states in which they can be, or are, transcribed. This review will attempt to summarize our current understanding of the structure and organization of ribosomal chromatin.