The contradictory definitions of heterochromatin: transcription and silencing.
Eukaryotic genomes are packaged in two general varieties of chromatin: gene-rich euchromatin and gene-poor heterochromatin. Each type of chromatin has been defined by the presence of distinct chromosomal proteins and posttranslational histone modifications. This review addresses recent findings that appear to blur the definitions of euchromatin and heterochromatin by pointing to the presence of typically heterochromatic modifications (including H3K9me) in euchromatin and typically euchromatic enzymes (including RNA polymerases) in heterochromatin. We discuss the implications of these new findings for the current definition of heterochromatin.
Huisinga
Kathryn L
KL
Department of Biology, Washington University, Saint Louis, MO 63130, USA.
Brower-Toland
Brent
B
Elgin
Sarah C R
SC
D000818:Animals; D022041:Euchromatin / Q000502:physiology; D020868:Gene Silencing; D006570:Heterochromatin / Q000502:physiology; D012319:RNA Polymerase II / Q000502:physiology; D034741:RNA, Small Interfering / Q000502:physiology; D009626:Terminology as Topic; D014158:Transcription, Genetic
D022041:Euchromatin; D006570:Heterochromatin; D034741:RNA, Small Interfering; D012319:RNA Polymerase II