Bifunctional Glyoxylate Cycle Protein of Caenorhabditis elegans: A Developmentally Regulated Protein of Intestine and Muscle

摘要

Thereactionofanabundant106-kDapolypeptidewithaspecificmonoclonalantibodyhasbeenlocalizedinintestinalandmusclecellsofthenematodeemCaenorhabditiselegans/em.Thisproteinwasfirstdetectedin4-6cellsoftheclonalElineageof100-cellembryos.Thislineageiscommittedtotheintestinalcellfate.Theantigencontinuedtobeexpressedinthedifferentiatinggutandthenappearedinearlydifferentiatingbodywallmusclecellsof400-to500-cellembryos.MolecularcloningandsequencingshowedthatthelargestcDNAclonecontained3274bpandencodedasequenceof1005aminoacids.Thepredictedpolypeptideof112,799MWcontainsseparatedomainsfortheglyoxylatecycleenzymesisocitratelyaseandmalatesynthase.TheirenzymaticactivitieshadbeenshownpreviouslytobehighestinembryosandL1larvae(Khan,F.R.,andMcFadden,B.A.(1980).emFEBSLett./em115,312-314;Khan,F.R.,andMcFadden,B.A.(1982).emExp.Parasitol./em54,48-54;Wadsworth,W.G.,andRiddle,D.L.(1989).emDev.Biol./em132,167-173).Thedomain-specificsequenceswereshowntobecontiguousingenomicDNAandareseparatedbyanintronof68bp.Asinglepolypeptideandbothenzymaticactivitiesareprecipitatedbytheantibody,andpeptidefragmentsresultingfromlimitedproteolyticdigestioncontainedaminoacidsequenceswhichoverlapthepredictedjunctionalregion.ThephysicallocalizationofthegenecorrelateswithasmallregionoftheleftarmofLinkageGroupVtowhichmultipleembryoniclethalmutationshavebeenmapped./p/div