The histone code and epigenetic inheritance
Part 1. Genetics
Published Online: 15 JUL 2005
Copyright © 2005 John Wiley & Sons, Ltd
Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics
How to Cite
Hoffman, A. R. and Vu, T. H. 2005. The histone code and epigenetic inheritance. Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics. 1:1.3:27.
- Published Online: 15 JUL 2005
The role of histones as active participants in gene regulation has only recently been appreciated. Previously, these proteins, which are assembled into nucleosomes, forming beads around which the DNA is wrapped, were considered to be relatively inert scaffolding for packaging the genetic material. However, the histones' amino-terminal tails extend away from the central core, and are thus available for posttranslational, reversible acetylation, methylation, phosphorylation, ADP-ribosylation, and ubiquitination. Amino acids in the histone cores may also be modified in a similar way. The enzymes responsible for these modifications are often specific for particular histones and for restricted amino acid residues. The array and combination of these specific attachments to the various histones have been postulated to constitute a code that may entail thousands of histone isoforms and that may make it possible to determine how these proteins will interact with their nearby DNA sequences. Histone modifications interact with DNA methylation to mark genes for silencing or transcription. In conjunction with DNA methylation, the histone code constitutes a heritable epigenetic signature that is faithfully replicated in daughter cells after cell division. The mechanism for transmitting the histone code to subsequent generations of cells remains to be fully elucidated. The study of the histone code is examined through the prism of the regulation of genomic imprinting. By reading the combinatorial and/or sequential histone modifications that constitute the histone code, it may be possible to predict which gene products will be transcribed and thus determine a cell's RNA repertoire and ultimately its proteome, just as reading the DNA code allows us to predict the encoded protein sequence.
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