H3.3 histone A
The information on this page was automatically extracted from online scientific databases.
From NCBI Gene:
Histones are basic nuclear proteins that are responsible for the nucleosome structure of the chromosomal fiber in eukaryotes. Two molecules of each of the four core histones (H2A, H2B, H3, and H4) form an octamer, around which approximately 146 bp of DNA is wrapped in repeating units, called nucleosomes. The linker histone, H1, interacts with linker DNA between nucleosomes and functions in the compaction of chromatin into higher order structures. This gene contains introns and its mRNA is polyadenylated, unlike most histone genes. The protein encoded is a replication-independent member of the histone H3 family. [provided by RefSeq, Jul 2008]
Variant histone H3 which replaces conventional H3 in a wide range of nucleosomes in active genes. Constitutes the predominant form of histone H3 in non-dividing cells and is incorporated into chromatin independently of DNA synthesis. Deposited at sites of nucleosomal displacement throughout transcribed genes, suggesting that it represents an epigenetic imprint of transcriptionally active chromatin. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template. Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling.
H3F3A and H3F3B mutations affecting residues involved in post-translational modifications of histone H3.3 are implicated in the pathogenesis of some bone and cartilage neoplasms. Mutations have been found with high prevalence in chondroblastoma and giant cell tumors of bone, and with low frequency in osteosarcoma, conventional chondrosarcoma and clear cell chondrosarcoma. Chondroblastoma samples frequently carry a H3F3B mutation affecting residue Lys-37 (H3K36), although H3F3A is mutated in some cases. Most giant cell tumors of bone harbor H3F3A mutations affecting residue Gly-35 (H3G34).
Glioma (GLM): Gliomas are benign or malignant central nervous system neoplasms derived from glial cells. They comprise astrocytomas and glioblastoma multiforme that are derived from astrocytes, oligodendrogliomas derived from oligodendrocytes and ependymomas derived from ependymocytes. [MIM:137800]