Information om | Engelska ordet HISTONES

Exempel på hur man kan använda HISTONES i en mening

• In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells the most important of these proteins are the histones.
• In biology, histones are highly basic proteins abundant in lysine and arginine residues that are found in eukaryotic cell nuclei and in most Archaeal phyla.
• Each nucleosome is composed of a little less than two turns of DNA wrapped around a set of eight proteins called histones, which are known as a histone octamer.
• These enzymes oxidize N-methyl groups, which occur in histones, in lysine derivatives, and in some forms of DNA.
• The first molecular chaperones discovered were a type of assembly chaperones which assist in the assembly of nucleosomes from folded histones and DNA.
• The attachment of methyl groups occurs predominantly at specific lysine or arginine residues on histones H3 and H4.
• Originally, they were separated from the other archaea based on rRNA sequences; other physiological features, such as lack of histones, have supported this division, although some crenarchaea were found to have histones.
• While these means of transcriptional regulation also exist in eukaryotes, the transcriptional landscape is significantly more complicated both by the number of proteins involved as well as by the presence of introns and the packaging of DNA into histones.
• DNA is, however, supercoiled and wound around "packaging" proteins called histones (in eukaryotes), and both superstructures are vulnerable to the effects of DNA damage.
• DNA-binding proteins include transcription factors which modulate the process of transcription, various polymerases, nucleases which cleave DNA molecules, and histones which are involved in chromosome packaging and transcription in the cell nucleus.
• Protamines are small, arginine-rich, nuclear proteins that replace histones late in the haploid phase of spermatogenesis and are believed essential for sperm head condensation and DNA stabilization.
• The proteins combined with DNA are histones and protamines; the resulting nucleoproteins are located in chromosomes.
• One example of the unique differences for thermoacidophilic archaea is their lack of eukaryote-like histones, which are typically involved in the packaging and reorganization of the chromosome, all Thermoplasma and Crenarchaeota lack histone like proteins.
• David Allis and Michael Grunstein, for their discovery that histones and histone acetylation directly regulate transcription.
• Ionic extraction of linker histones from native or reconstituted chromatin promotes its unfolding under hypotonic conditions from fibers of 30 nm width to beads-on-a-string nucleosome arrays.
• Acetylation of histones is thought to relax condensed heterochromatin as the negative charge of acetyl groups can repel the DNA phosphate backbone charges, thus reducing the histone binding affinity for DNA.
• Processing of core histones is done differently because typical histone mRNA lacks several features of other eukaryotic mRNAs, such as poly(A) tail and introns.
• HATs form large multiprotein complexes that weaken the association of histones to DNA by acetylating the N-terminal histone tail.
• Addition of methyl groups to histones by histone methyltransferases, can either activate or further repress transcription, depending on the amino acid being methylated and the presence of other methyl or acetyl groups in the vicinity.
• The nucleosome is the basic unit of DNA condensation and consists of a DNA double helix bound to an octamer of core histones (2 dimers of H2A and H2B, and an H3/H4 tetramer).

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