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H3k79me2
H3K79me2 is an epigenetic modification to the DNA packaging protein Histone H3. It is a mark that indicates the di-methylation at the 79th lysine residue of the histone H3 protein. H3K79me2 is detected in the transcribed regions of active genes. Nomenclature H3K79me2 indicates dimethylation of lysine 79 on histone H3 protein subunit: Lysine Methylation This diagram shows the progressive methylation of a lysine residue. The di-methylation denotes the methylation present in H3K79me2. Histone modifications The genomic DNA of eukaryotic cells is wrapped around special protein molecules known as Histones. The complexes formed by the looping of the DNA are known as chromatin. The basic structural unit of chromatin is the nucleosome: this consists of the core octamer of histones (H2A, H2B, H3 and H4) as well as a linker histone and about 180 base pairs of DNA. These core histones are rich in lysine and arginine residues. The carboxyl (C) terminal end of these histones contribute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epigenetic
In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in the DNA sequence. The Greek prefix '' epi-'' ( "over, outside of, around") in ''epigenetics'' implies features that are "on top of" or "in addition to" the traditional genetic basis for inheritance. Epigenetics most often involves changes that affect the regulation of gene expression, but the term can also be used to describe any heritable phenotypic change. Such effects on cellular and physiological phenotypic traits may result from external or environmental factors, or be part of normal development. The term also refers to the mechanism of changes: functionally relevant alterations to the genome that do not involve mutation of the nucleotide sequence. Examples of mechanisms that produce such changes are DNA methylation and histone modification, each of which alters how genes are expressed without altering the underlying DNA sequence. Gene expression can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ENCODE
The Encyclopedia of DNA Elements (ENCODE) is a public research project which aims to identify functional elements in the human genome. ENCODE also supports further biomedical research by "generating community resources of genomics data, software, tools and methods for genomics data analysis, and products resulting from data analyses and interpretations." The current phase of ENCODE (2016-2019) is adding depth to its resources by growing the number of cell types, data types, assays and now includes support for examination of the mouse genome. History ENCODE was launched by the US National Human Genome Research Institute (NHGRI) in September 2003. Intended as a follow-up to the Human Genome Project, the ENCODE project aims to identify all functional elements in the human genome. The project involves a worldwide consortium of research groups, and data generated from this project can be accessed through public databases. The initial release of ENCODE was in 2013 and since has be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyllysine
Methyllysine is derivative of the amino acid residue lysine where the sidechain ammonium group has been methylated one or more times. Such methylated lysines play an important role in epigenetics; the methylation of specific lysines of certain histones in a nucleosome alters the binding of the surrounding DNA to those histones, which in turn affects the expression of genes on that DNA. The binding is affected because the effective radius of the positive charge is increased (methyl groups are larger than the hydrogen atoms they replace), reducing the strongest potential electrostatic attraction with the negatively charged DNA. It is thought that the methylation of lysine (and arginine) on histone tails does not directly affect their binding to DNA. Rather, such methyl marks recruit other proteins that modulate chromatin structure. In Protein Data Bank The Protein Data Bank (PDB) is a database for the three-dimensional structural data of large biological molecules, such as pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histone Methyltransferase
Histone methyltransferases (HMT) are histone-modifying enzymes (e.g., histone-lysine N-methyltransferases and histone-arginine N-methyltransferases), that catalyze the transfer of one, two, or three methyl groups to lysine and arginine residues of histone proteins. The attachment of methyl groups occurs predominantly at specific lysine or arginine residues on histones H3 and H4. Two major types of histone methyltranferases exist, lysine-specific (which can be SET (Su(var)3-9, Enhancer of Zeste, Trithorax) domain containing or non-SET domain containing) and arginine-specific. In both types of histone methyltransferases, S-Adenosyl methionine (SAM) serves as a cofactor and methyl donor group. The genomic DNA of eukaryotes associates with histones to form chromatin. The level of chromatin compaction depends heavily on histone methylation and other post-translational modifications of histones. Histone methylation is a principal epigenetic modification of chromatin that determines ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histone Methylation
Histone methylation is a process by which methyl groups are transferred to amino acids of histone proteins that make up nucleosomes, which the DNA double helix wraps around to form chromosomes. Methylation of histones can either increase or decrease transcription of genes, depending on which amino acids in the histones are methylated, and how many methyl groups are attached. Methylation events that weaken chemical attractions between histone tails and DNA increase transcription because they enable the DNA to uncoil from nucleosomes so that transcription factor proteins and RNA polymerase can access the DNA. This process is critical for the regulation of gene expression that allows different cells to express different genes. Function Histone methylation, as a mechanism for modifying chromatin structure is associated with stimulation of neural pathways known to be important for formation of long-term memories and learning. Animal models have shown methylation and other epigenetic re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tn5 Transposon
A transposase is any of a class of enzymes capable of binding to the end of a transposon and catalysing its movement to another part of a genome, typically by a cut-and-paste mechanism or a replicative mechanism, in a process known as transposition. The word "transposase" was first coined by the individuals who cloned the enzyme required for transposition of the Tn3 transposon. The existence of transposons was postulated in the late 1940s by Barbara McClintock, who was studying the inheritance of maize, but the actual molecular basis for transposition was described by later groups. McClintock discovered that some segments of chromosomes changed their position, jumping between different loci or from one chromosome to another. The repositioning of these transposons (which coded for color) allowed other genes for pigment to be expressed. Transposition in maize causes changes in color; however, in other organisms, such as bacteria, it can cause antibiotic resistance. Transposition is al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ATAC-seq
ATAC-seq (Assay for Transposase-Accessible Chromatin using sequencing) is a technique used in molecular biology to assess genome-wide chromatin accessibility. In 2013, the technique was first described as an alternative advanced method for MNase-seq, FAIRE-Seq and DNase-Seq. ATAC-seq is a faster and more sensitive analysis of the epigenome than DNase-seq or MNase-seq. Description ATAC-seq identifies accessible DNA regions by probing open chromatin with hyperactive mutant Tn5 Transposase that inserts sequencing adapters into open regions of the genome. While naturally occurring transposases have a low level of activity, ATAC-seq employs the mutated hyperactive transposase. In a process called "tagmentation", Tn5 transposase cleaves and tags double-stranded DNA with sequencing adaptors. The tagged DNA fragments are then purified, PCR-amplified, and sequenced using next-generation sequencing. Sequencing reads can then be used to infer regions of increased accessibility as well as to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MNase-seq
MNase-seq, short for micrococcal nuclease digestion with deep sequencing, is a molecular biological technique that was first pioneered in 2006 to measure nucleosome occupancy in the ''C. elegans'' genome, and was subsequently applied to the human genome in 2008. Though, the term ‘MNase-seq’ had not been coined until a year later, in 2009. Briefly, this technique relies on the use of the non-specific endo-exonuclease micrococcal nuclease, an enzyme derived from the bacteria ''Staphylococcus aureus'', to bind and cleave protein-unbound regions of DNA on chromatin. DNA bound to histones or other chromatin-bound proteins (e.g. transcription factors) may remain undigested. The uncut DNA is then purified from the proteins and sequenced through one or more of the various Next-Generation sequencing methods.'' MNase-seq is one of four classes of methods used for assessing the status of the epigenome through analysis of chromatin accessibility. The other three techniques are DNase-se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ChIP-sequencing
ChIP-sequencing, also known as ChIP-seq, is a method used to analyze protein interactions with DNA. ChIP-seq combines chromatin immunoprecipitation (ChIP) with massively parallel DNA sequencing to identify the binding sites of DNA-associated proteins. It can be used to map global binding sites precisely for any protein of interest. Previously, ChIP-on-chip was the most common technique utilized to study these protein–DNA relations. Uses ChIP-seq is primarily used to determine how transcription factors and other chromatin-associated proteins influence phenotype-affecting mechanisms. Determining how proteins interact with DNA to regulate gene expression is essential for fully understanding many biological processes and disease states. This epigenetic information is complementary to genotype and expression analysis. ChIP-seq technology is currently seen primarily as an alternative to ChIP-chip which requires a hybridization array. This introduces some bias, as an array is restrict ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histone Code
The histone code is a hypothesis that the transcription of genetic information encoded in DNA is in part regulated by chemical modifications (known as ''histone marks'') to histone proteins, primarily on their unstructured ends. Together with similar modifications such as DNA methylation it is part of the epigenetic code. Histones associate with DNA to form nucleosomes, which themselves bundle to form chromatin fibers, which in turn make up the more familiar chromosome. Histones are globular proteins with a flexible N-terminus (taken to be the tail) that protrudes from the nucleosome. Many of the histone tail modifications correlate very well to chromatin structure and both histone modification state and chromatin structure correlate well to gene expression levels. The critical concept of the histone code hypothesis is that the histone modifications serve to recruit other proteins by specific recognition of the modified histone via protein domains specialized for such purposes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histone H3
Histone H3 is one of the five main histones involved in the structure of chromatin in eukaryotic cells. Featuring a main globular domain and a long N-terminal tail, H3 is involved with the structure of the nucleosomes of the 'beads on a string' structure. Histone proteins are highly post-translationally modified however Histone H3 is the most extensively modified of the five histones. The term "Histone H3" alone is purposely ambiguous in that it does not distinguish between sequence variants or modification state. Histone H3 is an important protein in the emerging field of epigenetics, where its sequence variants and variable modification states are thought to play a role in the dynamic and long term regulation of genes. Epigenetics and post-translational modifications The N-terminus of H3 protrudes from the globular nucleosome core and is susceptible to post-translational modification that influence cellular processes. These modifications include the covalent attachment ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
H3K36me3
H3K36me3 is an epigenetic modification to the DNA packaging protein Histone H3. It is a mark that indicates the tri- methylation at the 36th lysine residue of the histone H3 protein and often associated with gene bodies. There are diverse modifications at H3K36 and have many important biological processes. H3K36 has different acetylation and methylation states with no similarity to each other. Nomenclature H3K36me3 indicates trimethylation of lysine 36 on histone H3 protein subunit: Lysine Methylation This diagram shows the progressive methylation of a lysine residue. The tri-methylation denotes the methylation present in H3K36me3. Understanding histone modifications The genomic DNA of eukaryotic cells is wrapped around special protein molecules known as Histones. The complexes formed by the looping of the DNA are known as chromatin. The basic structural unit of chromatin is the nucleosome: this consists of the core octamer of histones (H2A, H2B, H3 and H4) as well ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
