Variant histone H2A which can replace H2A in some nucleosomes. 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. This variant is enriched at promoters, it may keep them in a repressed state until the appropriate activation signal is received (PubMed:11000274, PubMed:11081628, PubMed:11090616, PubMed:11509669, PubMed:12628191, PubMed:14645854, PubMed:14690608, PubMed:15045029, PubMed:16239142, PubMed:16344463, PubMed:16543223). Near telomeres, it may counteract gene silencing caused by the spread of heterochromatin proteins (PubMed:16543222). Required for the RNA polymerase II and SPT15/TBP recruitment to the target genes (PubMed:11509669). Involved in chromosome stability (PubMed:15353583). Required to target MPS3 to the inner membrane of the nuclear envelope (PubMed:21518795). 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 (Probable). The octamer wraps approximately 147 bp of DNA. H2A or its variant H2A.Z forms a heterodimer with H2B. H2A.Z associates with the VPS72/SWC2 subunit of the SWR1 chromatin remodeling complex. Interacts also with RBP1/DNA-directed RNA polymerase II largest subunit (PubMed:11509669). Interacts with NAP1 (PubMed:14645854, PubMed:14690608, PubMed:15045029, PubMed:16299513, PubMed:18086883). Interacts with MPS3 (PubMed:21518795). Acetylated by ESA1, a component of the NuA4 histone acetyltransferase (HAT) complex, and/or by GCN5, a component of the SAGA complex, to form H2A.ZK3Ac, H2A.ZK8Ac, H2A.ZK10Ac and H2A.ZK14Ac once deposited into chromatin (PubMed:16543223). Acetylation is required for function at telomeres (PubMed:16543222). H2A.ZK14Ac is acetylated at the promoters of active genes (PubMed:16543223). Present with 2840 molecules/cell in log phase SD medium. In contrast to H2A1 and H2A2, appears to be weakly or not sumoylated. Belongs to the histone H2A family. To ensure consistency between histone entries, we follow the 'Brno' nomenclature for histone modifications, with positions referring to those used in the literature for the 'closest' model organism. Due to slight variations in histone sequences between organisms and to the presence of initiator methionine in UniProtKB/Swiss-Prot sequences, the actual positions of modified amino acids in the sequence generally differ. In this entry the following conventions are used: H2A.ZK3ac = acetylated Lys-4; H2A.ZK8ac = acetylated Lys-9; H2A.ZK10ac = acetylated Lys-11; H2A.ZK14ac = acetylated Lys-15.