Transcription 619 Structure and function of ribosomal RNA gene chromatin

Transcription of the major ribosomal RNAs by Pol I (RNA polymerase I) is a key determinant of ribosome biogenesis, driving cell growth and proliferation in eukaryotes. Hundreds of copies of rRNA genes are present in each cell, and there is evidence that the cellular control of Pol I transcription involves adjustments to the number of rRNA genes actively engaged in transcription, as well as to the rate of transcription from each active gene. Chromatin structure is inextricably linked to rRNA gene activity, and the present review highlights recent advances in this area