Percent of the 150 tandem repeats of the rDNA that are actively transcribed in a typical cell

Range ~50 %
Organism Budding yeast Saccharomyces cerevisiae
Reference Woolford JL Jr, Baserga SJ. Ribosome biogenesis in the yeast Saccharomyces cerevisiae. Genetics. 2013 Nov195(3):643-81. doi: 10.1534/genetics.113.153197. p.647 right column 2nd paragraphPubMed ID24190922
Primary Source Toussaint, M., G. Levasseur, M. Tremblay, M. Paquette, and A. Conconi, 2005 Psoralen photocrosslinking, a tool to study the chromatin structure of RNA polymerase I–transcribed ribosomal genes. Biochem. Cell Biol. 83: 449–459.PubMed ID16094448
Method [Primary source abstract:] "...the technique of psoralen photocrosslinking has been used successfully both in vitro and in vivo."
Comments "In a typical yeast cell, only about half of the 150 tandem repeats of the rDNA [BNID 100243] are being actively transcribed. The others are maintained in a transcriptionally inactive state. This ratio of active to inactive rDNA genes was discovered by their differential accessibility to the intercalator, psolaren (primary source). The actively transcribed rRNA genes are devoid of histones and are instead covered with the Hmo1 protein (analogous to UBF1 in mammals)."
Entered by Uri M
ID 110024