P28，a28kDproteinfromtoad(Bufobufogargarizans)oocytes,wasidentifiedbyusingP13^suc1-agaroseaffinitychromatography.Sequencehomologyanalysisofthefull-lengthcDNAofP28(GeneBankaccessionnumber:AF314091)indicatedthatitencodesaproteincontaining224amino-acidswithabout55%iden-titiesandmorethan70%positivestoencodesaproteincontaining224amino-acidswithabout55%iden-titiesandmorethan70%positivestohuman,ratormouseUCH-L1,andcontainshomologicalfunctionaldomainsofUCHfamily.Anti-p28monoclonalantibody,oninjectingintotheoocytes,couldinhibittheprogesterone-inducedresumptionofmeioticpisioninadose-dependentmanner.TherecombinantproteinP28showedsimilarSDS/PAGEbehaviorstothenativeone,andpromotedubiquitinethylesterhydrolysis,aclassicalcatalyticreactionforubiquitincarboxylterminalhydrolases(UCHs).Theresultsinthispaperrevealthatanovelprotein,p28,existsinthetoadoocytes,isaUCHLlhomolog,wasengagedintheprocessofprogesterone-inducedoocytematurationpossiblythroughaninvolvementinproteinturnoveranddegradation.
