Control of mRNA translation in oocytes and developing embryos of giant moths: I. Function of the 5′ terminal “cap” in the tobacco hornworm, Manduca sexta☆

[摘要] Injectionoflabeledleucineintooocytesanddevelopingembryosofthetobaccohornworm,Manducasexta,revealedthattherateofproteinsynthesisincreasesdramaticallyafterfertilizationandcontinuestoriseuntilgastrulation.Cell-freepreparationsofoocytesanddevelopingembryosshowasimilarpatternofinvitroincorporation.WhenmessengerRNAextractedfromunfertilizedoocyteswasexaminedbygradientdensitycentrifugationunderdenaturingconditions,abroadpeakwasobservedwhichcenteredaround15S.IncontrasttomRNAextractedfromoocytes,thatfromembryoswasfoundtobecappedby7-methylguanosineatthe5′terminus.WhentranslationofoocytemRNAwascomparedwiththatofembryomRNAinacell-freetranslationsystemderivedfromwheatgerm,oocyteRNAtranslatedlessefficiently.Inthepresenceofaninhibitorofmethylation,S-adenosylhomocysteine,thedifferenceswerefurtherwidened.Incompetitionwithacapanalog,7-methylguanosine5′-monophosphate,embryomRNAtranslationwasinhibitedmorethanoocyteatlowconcentrationsofanalog.Theseresultsaretakentoindicatethatthelackofacapatthe5′terminuscouldbeonemechanismtoinhibittranslationpriortofertilization.

[学科分类] 生物科学（综合）