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. The nucleosome is a histone octamer containing two molecules each of H2A, H2B, H3 and H4 assembled in one H3-H4 heterotetramer and two H2A-H2B heterodimers. The octamer wraps approximately 147 bp of DNA. Interacts with zmynd11; when trimethylated at 'Lys-36' (H3.3K36me3). Expressed during S phase, then expression strongly decreases as cell division slows down during the process of differentiation. Specific interaction of trimethylated form at 'Lys-36' (H3.3K36me3) with zmynd11 is mediated by the encapsulation of Ser-32 residue with a composite pocket formed by the tandem bromo-PWWP domains. Acetylation is generally linked to gene activation. Acetylation on Lys-19 (H3K18ac) and Lys-24 (H3K24ac) favors methylation at Arg-18 (H3R17me). Acetylation at Lys-123 (H3K122ac) by EP300/p300 plays a central role in chromatin structure: localizes at the surface of the histone octamer and stimulates transcription, possibly by promoting nucleosome instability (By similarity). Asymmetric dimethylation at Arg-18 (H3R17me2a) is linked to gene activation. Asymmetric dimethylation at Arg-3 (H3R2me2a) by prmt6 is linked to gene repression and is mutually exclusive with H3 Lys-5 methylation (H3K4me2 and H3K4me3). H3R2me2a is present at the 3' of genes regardless of their transcription state and is enriched on inactive promoters, while it is absent on active promoters (By similarity). Specifically enriched in modifications associated with active chromatin such as methylation at Lys-5 (H3K4me), Lys-37 (H3K36me) and Lys-80 (H3K79me) are linked to gene activation. Methylation at Lys-5 (H3K4me) facilitates subsequent acetylation of H3 and H4. Methylation at Lys-80 (H3K79me) is associated with DNA double-strand break (DSB) responses and is a specific target for tp53bp1. Methylation at Lys-10 (H3K9me) and Lys-28 (H3K27me) are linked to gene repression. Methylation at Lys-10 (H3K9me) is a specific target for HP1 proteins (cbx1, cbx3 and cbx5) and prevents subsequent phosphorylation at Ser-11 (H3S10ph) and acetylation of H3 and H4. Methylation at Lys-5 (H3K4me) and Lys-80 (H3K79me) require preliminary monoubiquitination of H2B at 'Lys-120' (By similarity). Phosphorylated at Thr-4 (H3T3ph) by HASPIN during prophase and dephosphorylated during anaphase. Phosphorylation at Ser-11 (H3S10ph) by aurkb is crucial for chromosome condensation and cell-cycle progression during mitosis and meiosis. In addition phosphorylation at Ser-11 (H3S10ph) 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. Phosphorylation at Ser-11 (H3S10ph), which is linked to gene activation, prevents methylation at Lys-10 (H3K9me) but facilitates acetylation of H3 and H4. Phosphorylation at Ser-11 (H3S10ph) by aurkb mediates the dissociation of HP1 proteins (cbx1, cbx3 and cbx5) from heterochromatin. Phosphorylation at Ser-11 (H3S10ph) is also an essential regulatory mechanism for neoplastic cell transformation. Phosphorylated at Ser-29 (H3S28ph) by map3k20 isoform 1, rps6ka5 or aurkb during mitosis or upon ultraviolet B irradiation. Phosphorylation at Thr-7 (H3T6ph) by prkcb is a specific tag for epigenetic transcriptional activation that prevents demethylation of Lys-5 (H3K4me) by lsd1/kdm1a. At centromeres, specifically phosphorylated at Thr-12 (H3T11ph) from prophase to early anaphase, by DAPK3 and PKN1. Phosphorylation at Thr-12 (H3T11ph) by PKN1 or isoform M2 of PKM (PKM2) is a specific tag for epigenetic transcriptional activation that promotes demethylation of Lys-10 (H3K9me) by kdm4c/jmjd2c. Phosphorylation at Tyr-42 (H3Y41ph) by jak2 promotes exclusion of cbx5 (HP1 alpha) from chromatin. Phosphorylation on Ser-32 (H3S31ph) is specific to regions bordering centromeres in metaphase chromosomes. Monoubiquitinated by rag1 in lymphoid cells, monoubiquitination is required for V(D)J recombination. Lysine deamination at Lys-5 (H3K4all) to form allysine only takes place on H3K4me3 and results in gene repression. Butyrylation of histones marks active promoters and competes with histone acetylation. It is present during late spermatogenesis. Succinylation at Lys-80 (H3K79succ) by KAT2A takes place with a maximum frequency around the transcription start sites of genes. It gives a specific tag for epigenetic transcription activation. Desuccinylation at Lys-123 (H3K122succ) by SIRT7 in response to DNA damage promotes chromatin condensation and double-strand breaks (DSBs) repair. Serine ADP-ribosylation constitutes the primary form of ADP-ribosylation of proteins in response to DNA damage. Serine ADP-ribosylation at Ser-11 (H3S10ADPr) is mutually exclusive with phosphorylation at Ser-11 (H3S10ph) and impairs acetylation at Lys-10 (H3K9ac). Serotonylated by TGM2 at Gln-6 (H3Q5ser) during serotonergic neuron differentiation (By similarity). H3Q5ser is associated with trimethylation of Lys-5 (H3K4me3) and enhances general transcription factor IID (TFIID) complex-binding to H3K4me3, thereby facilitating transcription (By similarity). Dopaminylated by TGM2 at Gln-6 (H3Q5dop) in ventral tegmental area (VTA) neurons (By similarity). H3Q5dop mediates neurotransmission-independent role of nuclear dopamine by regulating relapse-related transcriptional plasticity in the reward system (By similarity). Lactylated in macrophages by EP300/P300 by using lactoyl-CoA directly derived from endogenous or exogenous lactate, leading to stimulates gene transcription. Belongs to the histone H3 family.