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H2AFB1
Histone H2A-Bbd type 1 also known as H2A Barr body-deficient is a histone variants, histone protein variant that in humans is encoded by the ''H2AFB1'' gene (H2A histone family, member B1). Function Histones are basic nuclear proteins that are responsible for the nucleosome structure of the chromosomal fiber in eukaryotes. Nucleosomes consist of approximately 146 bp of DNA wrapped around a histone octamer composed of pairs of each of the four core histones (histone H2A, H2A, Histone H2B, H2B, histone H3, H3, and histone H4, H4). The chromatin fiber is further compacted through the interaction of a linker histone, H1, with the DNA between the nucleosomes to form higher order chromatin structures. This gene encodes a member of the histone H2A family. This gene is part of a region that is repeated three times on chromosome X, once in intron 22 of the F8 gene and twice closer to the Xq telomere. This record represents the most centromeric copy which is in intron 22 of the F8 gene. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histone H2A
Histone H2A is one of the five main histone proteins involved in the structure of chromatin in eukaryotic cells. The other histone proteins are: H1, H2B, H3 and H4. Background Histones are proteins that package DNA into nucleosomes. Histones are responsible for maintaining the shape and structure of a nucleosome. One chromatin molecule is composed of at least one of each core histones per 100 base pairs of DNA. There are five families of histones known to date; these histones are termed H1/H5, H2A, H2B, H3, and H4. H2A is considered a core histone, along with H2B, H3 and H4. Core formation first occurs through the interaction of two H2A molecules. Then, H2A forms a dimer with H2B; the core molecule is complete when H3-H4 also attaches to form a tetramer. Sequence variants Histone H2A is composed of non-allelic variants. The term "Histone H2A" is intentionally non-specific and refers to a variety of closely related proteins that vary often by only a few amino acids. Apart ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histone Variants
Histone variants are proteins that substitute for the core canonical histones ( H3, H4, H2A, H2B) in nucleosomes in eukaryotes and often confer specific structural and functional features. The term might also include a set of linker histone (H1) variants, which lack a distinct canonical isoform. The differences between the core canonical histones and their variants can be summarized as follows: (1) canonical histones are replication-dependent and are expressed during the S-phase of cell cycle whereas histone variants are replication-independent and are expressed during the whole cell cycle; (2) in animals, the genes encoding canonical histones are typically clustered along the chromosome, are present in multiple copies and are among the most conserved proteins known, whereas histone variants are often single-copy genes and show high degree of variation among species; (3) canonical histone genes lack introns and use a stem loop structure at the 3’ end of their mRNA, whereas hist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histone H2B
Histone H2B is one of the 5 main histone proteins involved in the structure of chromatin in eukaryotic cells. Featuring a main globular domain and long N-terminal and C-terminal tails, H2B is involved with the structure of the nucleosomes. Structure Histone H2B is a lightweight structural protein made of 126 amino acids. Many of these amino acids have a positive charge at cellular pH, which allows them to interact with the negatively charged phosphate groups in DNA. Along with a central globular domain, histone H2B has two flexible histone tails that extend outwards – one at the N-terminal end and one at C-terminal end. These are highly involved in condensing chromatin from the beads-on-a-string conformation to a 30-nm fiber. Similar to other histone proteins, histone H2B has a distinct histone fold that is optimized for histone-histone as well as histone-DNA interactions. Two copies of histone H2B come together with two copies each of histone H2A, histone H3, and histone ... [...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] |
Histone H4
Histone H4 is one of the five main histone proteins involved in the structure of chromatin in eukaryote, eukaryotic cells. Featuring a main globular domain and a long N-terminus, N-terminal tail, H4 is involved with the structure of the nucleosome of the 'beads on a string' organization. Histone proteins are highly post-translationally modified. Covalently bonded modifications include acetylation and methylation of the N-terminal tails. These modifications may alter Gene expression, expression of genes located on DNA associated with its parent histone octamer. Histone H4 is an important protein in the structure and function of chromatin, where its sequence variants and variable modification states are thought to play a role in the dynamic and long term regulation of genes. Genetics Histone H4 is encoded in multiple genes at different loci including: HIST1H4A, HIST1H4B, HIST1H4C, HIST1H4D, HIST1H4E, HIST1H4F, HIST1H4G, HIST1H4H, HIST1H4I, HIST1H4J, HIST1H4K, HIST1H4L, HIST2H4A, H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromatin
Chromatin is a complex of DNA and protein found in eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important roles in reinforcing the DNA during cell division, preventing DNA damage, and regulating gene expression and DNA replication. During mitosis and meiosis, chromatin facilitates proper segregation of the chromosomes in anaphase; the characteristic shapes of chromosomes visible during this stage are the result of DNA being coiled into highly condensed chromatin. The primary protein components of chromatin are histones. An octamer of two sets of four histone cores (Histone H2A, Histone H2B, Histone H3, and Histone H4) bind to DNA and function as "anchors" around which the strands are wound.Maeshima, K., Ide, S., & Babokhov, M. (2019). Dynamic chromatin organization without the 30-nm fiber. ''Current opinion in cell biology, 58,'' 95–104. https://doi.o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
