Anti-Histone H3.3 K27I from rabbit

Histone H3.3 (UniProt: P84243) is encoded by the H3F3A (also known as H3.3A, H3F3, PP781, H3F3B, H3.3B) gene (Gene ID: 3020) in human. It is a highly conserved variant form of Histone H3, which replaces conventional H3 in a wide range of nucleosomes in active genes. Histone H 3.3 constitutes the predominant form of histone H3 in non-dividing cells and is incorporated into chromatin independently of DNA synthesis. H3.3 is associated with actively expressed genes in both animals and plants. It is predominantly enriched near transcription end sites (TES) of genes and positively associated with transcription. Histone H3 contains a main globular domain and a long N-terminal tail and is involved with the structure of the nucleosomes of the 'beads on a string' structure. The N-terminal tail of histone H3 protrudes from the globular nucleosome core and can undergo several different types of epigenetic modifications that influence cellular processes. These modifications include the covalent attachment of methyl or acetyl groups to lysine and arginine amino acids and the phosphorylation of serine or threonine. For example, acetylation on Lys10 (H3K9ac; initial methionine removed) impairs methylation at Arg9 (H3R8me2s) and acetylation on Lys19 (H3K18ac) and Lys24 (H3K24ac) favors methylation at Arg18 (H3R17me). Phosphorylation at Ser11 (H3S10ph) by Aurora kinase B is crucial for chromosome condensation and cell-cycle progression during mitosis and meiosis. Phosphorylation at Ser11 by RPS6KA4 and RPS6KA5 is important during interphase because it enables the transcription of genes following external stimulation, like mitogens, stress, growth factors or UV irradiation and result in the activation of genes, such as c-Fos and c-Jun. Mutations in Histone H3.3 have been implicated in a high proportion of malignant pediatric brain cancers. The mutant H3.3 histone disrupts epigenetic post-translational modifications near genes involved in cancer processes and in brain function. Histone H3K27 is reported to be methylated by the Polycomb Repressive Complex 2 (PRC2) for X-chromosome inactivation and gene silencing and H3K27M peptides are shown to be potent inhibitors of PRC2 activity. H3K27I peptide also displays inhibitory, although to a lesser extent, on PRC2. The possibility of K27I mutation in Histone H3 has been suggested in pediatric gliomas, which might be due to blockage of glial cell differentiation. (Ref.: Lewis, PW., and Allis, CD (2013). Cell Cycle. 12(20): 3241-3242).