▁ATP ▁dependent ▁chrom atin ▁rem od eling ▁complex es ▁and ▁hist one - mod ifying ▁en zym es ▁are ▁two ▁pre domin ant ▁factors ▁employed ▁to ▁accomplish ▁this ▁rem od eling ▁process . ▁ ▁Ch rom atin ▁relax ation ▁occurs ▁rapidly ▁at ▁the ▁site ▁of ▁a ▁DNA ▁damage . ▁ ▁This ▁process ▁is ▁initi ated ▁by ▁P AR P 1 ▁protein ▁that ▁starts ▁to ▁appear ▁at ▁DNA ▁damage ▁in ▁less ▁than ▁a ▁second , ▁with ▁half ▁maximum ▁accum ulation ▁within ▁ 1 . 6 ▁seconds ▁after ▁the ▁damage ▁occurs . ▁ ▁Next ▁the ▁chrom atin ▁rem od eler ▁Alc 1 ▁quickly ▁attach es ▁to ▁the ▁product ▁of ▁P AR P 1 , ▁and ▁comple tes ▁arrival ▁at ▁the ▁DNA ▁damage ▁within ▁ 1 0 ▁seconds ▁of ▁the ▁damage . ▁ ▁About ▁half ▁of ▁the ▁maximum ▁chrom atin ▁relax ation , ▁pres umably ▁due ▁to ▁action ▁of ▁Alc 1 , ▁occurs ▁by ▁ 1 0 ▁seconds . ▁This ▁then ▁allows ▁rec ruit ment ▁of ▁the ▁DNA ▁repair ▁en zym e ▁M RE 1 1 , ▁to ▁initi ate ▁DNA ▁repair , ▁within ▁ 1 3 ▁seconds . ▁▁ γ H 2 AX , ▁the ▁ph osph ory l ated ▁form ▁of ▁H 2 AX ▁is ▁also ▁involved ▁in ▁the ▁early ▁steps ▁leading ▁to ▁chrom atin ▁de cond ens ation ▁after ▁DNA ▁damage ▁occurrence . ▁ ▁The ▁hist one ▁variant ▁H 2 AX ▁constit utes ▁about ▁ 1 0 % ▁of ▁the ▁H 2 A ▁hist ones ▁in ▁human ▁chrom atin . ▁▁ γ H