| EntrezGeneSummary | HistonesarebasicnuclearproteinsthatareresponsIBLeforthenucleosomestructureofthechromosomalfiberineukaryotes.Twomoleculesofeachofthefourcorehistones(H2A,H2B,H3,andH4)formanoctamer,aroundwhichapproximately146bpofDNAiswrappedinrepeatingunits,callednucleosomes.Thelinkerhistone,H1,interactswithlinkerDNAbetweennucleosomesandfunctionsinthecompactionofchromatinintohigherorderstructures.ThisgeneencodesamemberofthehistoneH2Afamily,andgeneratestwotranscriptsthroughtheuseoftheconservedstem-loopterminationmotif,andthepolyAadditionmotif. | 
| UniProtSummary | FUNCTION:SwissProt:P16104#VarianthistoneH2AwhichreplacesconventionalH2Ainasubsetofnucleosomes.NucleosomeswrapandcompactDNAintochromatin,limitingDNAaccessibilitytothecellularmachinerieswhichrequireDNAasatemplate.Histonestherebyplayacentralroleintranscriptionregulation,DNArepair,DNAreplicationandchromosomalstABIlity.DNAaccessibilityisregulatedviaacomplexsetofpost-translationalmodificationsofhistones,alsocalledhistonecode,andnucleosomeremodeling.Requiredforcheckpoint-mediatedarrestofcellcycleprogressioninresponsetolowdosesofionizingrADIationandforefficientrepairofDNAdoublestrandbreaks(DSBs)specificallywhenmodifiedbyC-terminalphosphorylation. SIZE:143aminoacids;15145Da
 SUBUNIT:ThenucleosomeisahistoneoctamercontainingtwomoleculeseachofH2A,H2B,H3andH4assembledinoneH3-H4heterotetramerandtwoH2A-H2Bheterodimers.Theoctamerwrapsapproximately147bpofDNA.InteractswithnumerousproteinsrequiredforDNAdamagesignalingandrepairwhenphosphorylatedonSer-140.TheseincludeMDC1,TP53BP1,BRCA1andtheMRNcomplex,composedofMRE11A,RAD50,andNBN.InteractionwiththeMRNcomplexismediatedatleastinpartbyNBN.AlsointeractswithDHX9/NDHIIwhenphosphorylatedonSer-140.
 SUBCELLULARLOCATION:Nucleus.DEVELOPMENTALSTAGE:SynthesizedinG1aswellasinS-phase.
 DOMAIN:SwissProt:P16104The[ST]-QmotifconstitutesarecognitionsequenceforkinasesfromthePI3/PI4-kinasefamily.
 PTM:PhosphorylatedonSer-140(toformgamma-H2AFX)inresponsetoDNAdoublestrandbreaks(DSBs)generatedbyexogenousgenotoxicagentsandbystalledreplicationforks,andmayalsooccurduringmeioticrecombinationeventsandimmunoglobulinclassswitchinginlymphocytes.PhosphorylationcanextenduptoseveralthousandnucleosomesfromtheactualsiteoftheDSBandmaymarkthesurroundingchromatinforrecruitmentofproteinsrequiredforDNAdamagesignalingandrepair.Widespreadphosphorylationmayalsoservetoamplifythedamagesignaloraidrepairofpersistentlesions.PhosphorylationofSer-140inresponsetoionizingradiationismediatedbybothATMandPRKDCwhiledefectsinDNAreplicationinduceSer-140phosphorylationsubsequenttoactivationofATRandPRKDC.DephosphorylationofSer-140byPP2AisrequiredforDNADSBrepair.Inmeiosis,Ser-140phosphorylationmayoccuratsynaptonemalcomplexesduringleptoteneasanATM-dependentresponsetotheformationofprogrammedDSBsbySPO11.Ser-140phosphorylationmaysubsequentlyoccursatunsynapsedregionsofbothautosomesandtheXYbivalentduringzygotene,downstreamofATRandBRCA1activation.Ser-140phosphorylationmayalsoberequiredfortranscriptionalrepressionofunsynapsedchromatinandmeioticsexchromosomeinactivation(MSCI),wherebytheXandYchromosomescondenseinpachytenetoformtheheterochromaticXY-body.Duringimmunoglobulinclassswitchrecombinationinlymphocytes,Ser-140phosphorylationmayoccuratsitesofDNA-recombinationsubsequenttoactivationoftheactivation-inducedcytidinedeaminaseAICDA.&MonoubiquitinationofLys-120byRING1andRNF2/RING2complexgivesaspecifictagforepigenetictranscriptionalrepression(Bysimilarity).
 SIMILARITY:BelongstothehistoneH2Afamily.
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