Developmental regulation of multiple forms of UDPglucose pyrophosphorylase of Dictyostelium☆☆☆

[摘要] Uridinediphosphoglucosepyrophosphorylase(UTP:α-d-glucose-1-phosphateuridylyltransferase,EC2.7.7.9)isadevelopmentallyregulatedenzymeinDictyosteliumdiscoideumessentialforthecompletionofitslifecycle.Duringvegetativegrowthandtheearlystagesofdifferentiationthespecificactivityoftheenzymeremainsconstant.However,itincreasesthreefoldbythetimefruitingbodiesareformed.Wehaveidentifiedadevelopmentallyspecificformofuridinediphosphoglucosepyrophosphorylase,alteredinbothisoelectricpointandapparentmolecularweight,byresolvingcrudeextractsofcellsontwo-dimensionaldenaturingpolyacrylamidegels,renaturingtheproteininsitu,andlocalizingactiveenzymewithahistochemicalstain.Quantitationoftheamountofenzymestaindepositedinthegelsshowsthattheactivityinthenewformcanaccountfortheincreaseobservedindevelopment.Theappearanceofthedevelopmentalformoftheenzymerequiresdenovoproteinsynthesissinceitisinhibitedbycycloheximide.Immunoprecipitationofuridinediphosphoglucosepyrophosphorylasefrominvivoandinvitrosynthesizedproteinshasrevealedheterogeneitynotpreviouslydetectedintheenzymefrombothvegetativeanddevelopedcells.TwodifferentproteinsaresynthesizedinvitrobymRNAfromeithervegetativeordevelopedcells.Thesetwoproteinsarealsofoundinvivoindevelopedcells.Onlyoneofthetwoproteinsisfoundinvegetativecells.Enzymeproteinsynthesizedinvivoappearstobemodifiedaftertranslation.Therefore,theobservedheterogeneityinuridinediphosphoglucosepyrophosphorylasefoundinvivoappearsduebothtopost-translationalmodificationandtosynthesisoftwopolypeptidesfromoneormorespeciesofmRNA.

[学科分类] 生物科学（综合）