What type of protein is H2A?
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.
Is H2AX a protein?
H2A histone family member X (usually abbreviated as H2AX) is a type of histone protein from the H2A family encoded by the H2AFX gene. H2AX contributes to nucleosome-formation, chromatin-remodeling and DNA repair, and is also used in vitro as an assay for double-strand breaks in dsDNA.
What is H2AX?
H2AX is a variant of the H2A histone. When DNA undergoes double-strand break damage, H2AX is phosphorylated by ATM (or ATR). This phosphorylation of H2AX is named gamma-H2AX (y-H2AX). y-H2AX is not a marker for apoptosis; it is the starting point to recruit the DSB repair machinery.
What does Gamma-H2AX measure?
Phosphorylation of histone protein H2AX on serine 139 (gamma-H2AX) occurs at sites flanking DNA double-stranded breaks (DSBs) and can provide a measure of the number of DSBs within a cell.
Where is histone H-2A found?
While histones H3 and H4 form a tetrameric structure known as nucleosome core that is positioned in the inner region of the nucleosome, the histones H2A and H2B are rather located on the nucleosomal surface.
What is the difference between H-2A and H2B?
H-2A workers perform seasonal or temporary agricultural labor. They also engage in range herding and livestock production. H-2B workers perform temporary jobs in a variety of fields including landscaping, meat and seafood processing, and construction.
Where is H2AX found?
Histone H2AX is a histone variant found in almost all eukaryotes. It makes a central contribution to genome stability through its role in the signaling of DNA damage events and by acting as a foundation for the assembly of repair foci.
How is H2AX phosphorylated?
H2AX is phosphorylated at Ser-139 by the protein kinase ATM, which is activated in response to DSBs by auto-phosphorylation of Ser-1981 residues in inactive dimers. The PIKK kinases DNA-PKcs and ATR (predominantly in response to UV-mediated DSBs) also phosphorylate H2AX.
What is γ H2AX foci?
The γH2AX focus assay represents a fast and sensitive approach for the detection of one of the critical types of DNA damage – double-strand breaks (DSB) induced by various cytotoxic agents including ionising radiation.
Which of the chromatin is transcriptionally active?
Heterochromatin is densely packed and inaccessible to transcription factors so it is rendered transcriptionally silent (Richards and Elgin 2002). Euchromatin, on the other hand, is less condensed, more accessible, and therefore transcriptionally active (Hennig 1999).
What is difference between H-1B and H-2B visa?
Difference between H1B and H2B Visa H-1B visas are for the employment of skilled workforce who possess university degrees and experience in a certain domain. These applicants, if approved, are granted a period of three to six years. Whereas, H-2B visa holders are allowed for one year, with renewal for two years.
What is the role of H2AX in DNA repair?
During last few years several groups suggested that H2AX has an important function as a docking site for protein complexes that bind to broken DNA ends and promote chromatin remodeling to keep broken chromosomal DNA ends together [60, 63, 71].
Which is histone encoded in the H2AX gene?
“H2A.X. a histone isoprotein with a conserved C-terminal sequence, is encoded by a novel mRNA with both DNA replication type and polyA 3′ processing signals.” Cited for: NUCLEOTIDE SEQUENCE [MRNA]. “Tyrosine dephosphorylation of H2AX modulates apoptosis and survival decisions.” Cited for: PHOSPHORYLATION AT TYR-143, MUTAGENESIS OF TYR-143.
What is the role of H2AX in DDR?
Phosphorylation of H2AX plays a key role in DDR and is required for the assembly of DNA repair proteins at the sites containing damaged chromatin as well as for activation of checkpoints proteins which arrest the cell cycle progression. In general, analysis of H2AX expression can be used to detect the genotoxic effect of different toxic substances.
How is phosphorylation of H2AX mediated by DNA-PK?
DNA-PK mediates phosphorylation of H2AX in cells under hypertonic conditions and during apoptotic DNA fragmentation [28, 29]. However, DNA damage caused by ionizing radiation leads to phosphorylation of H2AX that is mediated by all PIKK kinases, ATM, ATR, and DNA-PK [30].