H2A.Z
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Histone H2A.Z is a
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
encoded by the ''H2AZ1''
gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. 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: protei ...
in humans.
Function
Histone 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. They act as spools around which DNA winds to create structural units called nucleosomes ...
s are basic nuclear proteins that are responsible for the
nucleosome A nucleosome is the basic structural unit of DNA packaging in eukaryotes. The structure of a nucleosome consists of a segment of DNA wound around eight histone, histone proteins and resembles thread wrapped around a bobbin, spool. The nucleosome ...
structure of the
chromosomal A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most importa ...
fiber in
eukaryote The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...
s. Nucleosomes consist of approximately 146 base pairs(bp) of DNA wrapped around a
histone 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. They act as spools around which DNA winds to create structural units called nucleosomes ...
octamer, which includes pairs of each of the four core histones ( H2A, H2B, H3, and H4). The
chromatin Chromatin is a complex of DNA and protein found in eukaryote, 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 r ...
fiber is further compacted by the interaction of a linker histone, H1, with the DNA between the nucleosomes to form higher order chromatin structures. The H2AFZ gene encodes a replication-independent member of the histone H2A family that is distinct from other members of the family. Biological Importance Studies in mice have shown that this particular histone is required for embryonic development and indicate that lack of functional histone H2A leads to embryonic lethality.
Histone H2AZ is a variant of histone H2A, and is used to mediate the thermosensory response, and is essential to perceive the ambient temperature. Nucleosome occupancy of H2A.Z decreases with temperature, and in vitro assays show that H2A.Z-containing nucleosomes wrap DNA more tightly than canonical H2A nucleosomes in
Arabidopsis ''Arabidopsis'' (rockcress) is a genus in the family Brassicaceae. They are small flowering plants related to cabbage and mustard. This genus is of great interest since it contains thale cress (''Arabidopsis thaliana''), one of the model organ ...
.(Cell 140: 136–147, 2010) However, some of the other studies (Nat. Genet. 41, 941–945 and Genes Dev., 21, 1519–1529) have shown that incorporation of H2A.Z in nucleosomes, when it co-occurs with H3.3, makes them weaker. Gene Expression and Chromatin Structure The positioning of H2A.Z containing nucleosomes around transcription start sites has been shown to affect the downstream gene expression. Recent evidence also points to a role for H2A.Z in repressing a subset of ncRNAs, derepressing CUTs, as well as mediation higher order chromatin structure formation.


References


Further reading

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External links


PDBe-KB
provides an overview of all the structure information available in the PDB for Human Histone H2A.Z Genes on human chromosome 4 {{gene-4-stub