histone


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histone

(hĭs`tōn), any of a class of proteinprotein,
any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellular dry weight.
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 molecules found in the chromosomes of eukaryotic cellscell,
in biology, the unit of structure and function of which all plants and animals are composed. The cell is the smallest unit in the living organism that is capable of integrating the essential life processes. There are many unicellular organisms, e.g.
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. They complex with the DNA (see nucleic acidnucleic acid,
any of a group of organic substances found in the chromosomes of living cells and viruses that play a central role in the storage and replication of hereditary information and in the expression of this information through protein synthesis.
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) and pack the DNA into tight masses of chromatin, which have the structure of coiled coils, much like a tangled telephone cord. The molecules are strongly basic and of relatively small size. They also serve a function in the transcription of DNA. The histones are rich in the amino acids argininearginine
, organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer participates in the biosynthesis of proteins.
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 and lysinelysine
, organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer appears in mammalian protein.
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; the five major subtypes of the class differ from one another chiefly in the relative amounts of these two amino acids. They have been greatly conserved during evolution, histone structures vary little in a wide range of organisms.

histone

[′hi‚stōn]
(biochemistry)
Any of the strong, soluble basic proteins of cell nuclei that are precipitated by ammonium hydroxide.
References in periodicals archive ?
Additionally, the accurate histone acetylation at auxin-controlled loci and the subsequently auxin responsive genes activation by specific histone acetyltransferases like the ELONGATOR and AtGCN5 (Nelissen et al.
Linking DNA methylation and histone modification: patterns and paradigms.
It has been previously documented that E2F1 is able to recruit other histone acetyltransferases such as GCN5 to acetylate localized H3K9 residues (Guo et al.
The histone proteins form larger complexes called nucleosomes around which the DNA is wound in the cell nucleus.
In the past, histones were thought of as spools around which DNA was wound.
Histone phosphorylation and chromatin structure during mitosis in Chinese hamster cells.
Recent findings have revealed that in addition to genetic mutations, such epigenetic modifications as DNA methylation, histone modifications, and the pro duction of noncoding micro-RNAs are key features in the regulation of gene transcription, replication, and DNA repair (5, 6).
While ADP ribosylation of histone Hl opens chromatin structure (13).
The researchers found stressed mice had much higher levels of histone methylation than non-stressed mice had.
Topics include DNA methylation and the mammalian genome, methods for the genome-wide and genome-specific analysis of DNA methylation levels and patterns, histone modifications, histone variants and nucleosome occupancy, molecular mechanisms of polycomb silencing, non-coding RNAs in gene regulation, plant epigenetics using a comparative approach, embryonic stem cell epigenetics, the biology of genomic imprinting, X chromosome inactivation, cancer epigenetics, the role of micro DNAs in human cancer, the impact of the environment on epigenetic regulation of gene expression and developmental programming, and trans-generational epigenetic inheritance.
acetylation, methylation, phosphorilation and others) to the histone proteins