SulfatecanbeactivatedbyATPsulfurylaseandadenosine5-phosphosulfatekinase(APSK)invivo.RecentstudiessuggestedthatAPSKinArabidopsisthalianaregulatedthepartitionbetweenAPSreductionandphosphorylationanditsactivitycanbemodulatedbycellularredoxstatus.InordertostudyregulationofAPSKinrice(OsAPSK),OsAPSKIgenewasclonedanditsactivitywasanalyzed.OsAPSKIC36andC69werefoundtobetheconservedcounterpartsofC86andC119,whichinvolvedindisulfideformationinAtAPSK.C36A/C69AOsAPSK1doublemutationwasmadebysitedirectedmutagenesis.OsAPSKanditsmutantwereprokaryoticallyover-expressedandpurified,andthenassayedforAPSphosphorylationactivity.OsAPSK1activitywasdepressedbyoxidizedglutathione,whiletheactivityofitsmutantwasnot.Furtherstudiesinthecasethatoxidativestresswillfluctuateinvivo3'-phosphoadenosine-5'-phosphosulfatecontent,andallAPSKisoenzymeshavesimilarregulationpatternsarenecessarytobeperformed.
