| Summary: | ) r Nhal-type antiporterswith differentsubstratespeciÍicity(or affinityto individualsubstrates) andfunctions.One of themis involvedin thedetoxificationof cells andtheothercouldplay an importantrole in the maintenanceof stableintracellularpotassiumcontent,cell volume andpH of thecýoplasmthanlsto its abilitytotransportK+. At this time, no yeast speciespossessingsolely a Na*/fI*antiporterwith narrow substratespecificity (for Na* and Li) is known;therefore,the physiologicalrole of Nhal- type antiportersseemsto be complexwith a participationboth in the eliminationof toxic cationsfromcells andin themaintenanceof stableintracellularK* concentration,cell volume andcýoplasmic pH. 4.Summary Themainresultsof thethesíscanbesummarizedas: o The studiesof sequencesof yeastalkali metalcation/Iťantiporters(Nhal, Nhxl andKhal families)in silico showedthatthe structureof all threegroupsof theseproteinsprobably contains 12 transmembranesegments,we found some conservedamino acid residuesor motifslikely to be importantforproperfunctioningof antiporters,andourphylogeneticstudy revealedthatNhxl proteinsare relatedto both plant and mammalianNa*/Iť antiporters, Khal antiportersare close to thebacterialrelativesandNhal-type proteinsform a soparate goup so far characteizedonly in yeastsor fungi. o The D. hanseniiNHAI geneencodesa...
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