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Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Sometimes one just isn’t enough: do vertebrates contain an H2A.Z hyper-variant? | Mehta et al. Journal of Biology 2010 9 3 http jbiol.eom content 9 1 3 Journal of Biology MINIREVIEW L__ Sometimes one just isn t enough do vertebrates contain an H2A.Z hyper-variant Monika Mehtan Hyun-Soo Kimn and Michael-Christopher Keogh See research articles http www.biomedcentral.Com 1741-7007 7 86 and http www.biomedcentral.Com 1471-2148 9 31 Abstract How much functional specialization can one component histone confer on a single nucleosome The histone variant H2A.Z seems to be an extreme example. Genome-wide distribution maps show non-random and evolutionarily conserved patterns with localized enrichment or depletion giving a tantalizing suggestion of function. Multiple post-translational modifications on the protein indicate further regulation. An additional layer of complexity has now been uncovered the vertebrate form is actually encoded by two non-allelic genes that differ by expression pattern and three amino acids. All species have to perform a balancing act with their genome cram it into the cell in the case of eukaryotes a small part of that cell for example about 2 m of human DNA in a nucleus of about 5 pm diameter yet make the appropriate regions readily available for replication and expression and repair if something goes wrong . Eukaryotes achieve this feat by wrapping their DNA into chromatin a highly ordered complex with a simple repeating unit of about 146 bp DNA plus eight histone proteins termed the nucleosome. This beads-on-a-string array is further assembled into a variety of higher-order structures all the way up to the metaphase chromosome. The chromatin field exploded with the discovery that the monotonous-looking nucleosomes are actually hugely variable with post-translational modifications of numerous residues on the major histones their substitution for histone variants and even post-translational modifications of the variants. Furthermore the highly These authors contributed equally to this work. Correspondence .
