Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: Histone modifications: from genome-wide maps to functional insights. | Opinion Histone modifications from genome-wide maps to functional insights Fred van Leeuwen and Bas van Steensel Address Netherlands Cancer Institute Plesmanlaan 121 1066 CX Amsterdam The Netherlands. Correspondence Fred van Leeuwen. E-mail . Bas van Steensel. E-mail Published 31 May 2005 Genome Biology 2005 6 113 doi gb-2005-6-6-113 The electronic version of this article is the complete one and can be found online at http 2005 6 6 113 2005 BioMed Central Ltd Abstract A large number of histone modifications has been implicated in the regulation of gene expression. Together these modifications have the potential to form a complex combinatorial regulatory code. Genome-wide mapping approaches provide new opportunities to decipher this code but they may suffer from systematic biases. Integration of datasets and improved technologies will provide the way forward. The DNA in the nucleus of a eukaryotic cell is packed into chromatin the fundamental building block of which the nucleosome consists of an octamer of the four histones H2A H2B H3 and H4 around which the DNA is wrapped. The histones within chromatin are subject to extensive post-translational modification including acetylation methylation phosphorylation ubiquitination and ribosylation. Many enzymes have been identified that are responsible for the addition or removal of modifications at one or a few specific histone amino-acid residues and many histone modifications are believed to play important roles in the regulation of transcription. Although some histone modifications may cause alterations in the structure or overall charge of the nucleosome 1 2 it is likely that most act by controlling the docking of specific regulatory factors. For example the chromodomain of heterochromatin protein 1 HP1 binds to the tail of histone H3 only when lysine 9 of H3 H3K9 is methylated and this may contribute to repression of transcription 3 . Similarly the .
