THEJOURNALOFBIOLOGICALCHEMISTRYVal.268,No.18,IssueofJune25,pp.1324@-13252199301993byTheAmericanSocietyforBiachemistryandMolecularBiology,Inc,Printedin~.S.A.SiteSpecificityofPeaHistoneAcetyltransferaseBinVitro”(Receivedforpublication,January11,1993,andinrevisedform,March1,1993)IsmaelMingarro,RamonSeadra,M.LuisaSalvador,andLuisFrancoSFromtheDepartmentofBiochemistryandMolecularBiology,UniversityofValenciu,E-46100Burjassot,Valencia,SpainHistoneacetyltransferaseBfrompeaembryonicThesecondhypothesisenvisageshistoneacetylationasaaxeshasbeenpurified-300-foldbyacombinationofsignalintroducedinthehistonesthatwouldallowthespecif-chromatographicprocedures,includingaffinitychro-icallyacetylatedN-terminaltailstoberecognizedbyaputa-matographyonhistone-agarose.Theenzymeprepara-tive(protein)factor.Thedifferentfunctionalrolesascribedtionhasbeenusedfortheinuitrotransferofacetyltohistoneacetylationmaythendependonthespecificusagegroupsfrom[l-‘4C]acetyl-CoAtonon-acetylatedpeaoflysinesandonthespecificityoftheseputativefactors.ThehistoneH4.Uptothreeacetylgroupscanbeintroducedintothehistone.Theresultingmono-,di-,andtriace-hypothesisisbaseduponthefactthathistoneacetylationtylatedH4isoformswereseparatedandsequencedtodoesnotoccuratrandom.Actually,bothsequencingstudiesdeterminetheacetylatedsites.Onlysites5,12,and16(PesisandMatthews,1986;Chicoineetal.,1986,1987;Coup-wereusedbyhistoneacetyltransferaseB,butnoclearpezetal.,1987;Richmanetal.,1988;Thorneetal.,1990)andpreferenceamongthemwasobserved.Theabsenceoftheuseofspecificantibodies(Linetal.,1989;Turner,1989;modificationofotherpotentiallyacetylatablesitesisTurnerandFellows,1989;Turneretal.,1989)haverevealedanotherindicationthatacetylationofthedifferentthatthepotentialsitesforacetylationaredifferentiallyusedlysineresiduesintheN-terminalH4tailservesa8ainthenaturallyoccurringmono-,di-,andtriacetylatedhis-specificsignalindifferentnuclearprocesses.toneisoforms.Takingintoaccountthatthereare26targetsitesforacetylationinanucleosome,