2 ▁over - expression ▁protect s ▁cells ▁against ▁H 2 O 2 - indu ced ▁damage ▁while ▁Gr x 2 ▁knock down ▁showed ▁the ▁opposite ▁effect . ▁The ▁protection ▁role ▁of ▁Gr x 2 ▁against ▁H 2 O 2 - indu ced ▁apo pt osis ▁is ▁likely ▁associated ▁with ▁its ▁ability ▁to ▁preserve ▁the ▁electron ▁transport ▁chain ▁complex ▁I . ▁In ▁addition ▁to ▁H 2 O 2 , ▁Gr x 2 a ▁over expression ▁is ▁resist ant ▁to ▁apo pt osis ▁induced ▁by ▁other ▁ox id ative ▁stress ▁re ag ents ▁( i . e ., ▁do x or ub ic in ▁( D ox ) ▁and ▁phen yl ars ine ▁ox ide ), ▁due ▁to ▁reduced ▁card i ol ip in ▁ox id ation ▁and ▁subsequent ▁cy to chrome ▁c ▁release . ▁Interest ing , ▁Gr x 2 ▁has ▁also ▁been ▁found ▁to ▁prevent ▁aggreg ation ▁of ▁mut ant ▁SO D 1 ▁in ▁mit och ond ria ▁and ▁abol ish ▁its ▁to x icity . ▁ ▁Being ▁a ▁re do x ▁sensor , ▁Gr x 2 ▁activity ▁is ▁tight ly ▁reg ulated ▁by ▁the ▁ox id ative ▁state ▁of ▁the ▁environment ▁via ▁iron - s ulf ur ▁cluster . ▁In ▁steady ▁state , ▁Gr x 2 ▁forms ▁dim ers ▁to ▁coordinate ▁iron - s ulf ur ▁clusters , ▁which ▁in ▁turn ▁in activ ate ▁Gr x 2 ’ s ▁activity ▁by ▁se quest ering ▁the ▁active - site ▁c yst e ines . ▁During ▁ox id ative ▁stress , ▁the ▁dim ers