BackgroundInformation | Theenzyme2",3"-cyclicnucleotide3"-phosphodi-esterase(CNP)isexpressedathighlevelsbyoligodendrocytesinthecentralnervoussystemandbySchwanncellsintheperipheralnervoussystem(Sprinkle,1989).Byvirtueofthiscell-specificexpression,CNPisrecognizedasacharacteristicMarkerforthesetwomyelin-producingglialcelltypes(Sprinkle,1989;Kimetal.,1984;Sheedlo&Sprinkle,1984;McMorrisetal.,1984).Beyonditsenzymaticactivityofcleavingthe2",3"-cyclicterminusofnucleotides(Sprinkle,1989),thephysiologicalroleofCNPisstillunderinvestigation.CNPactivityhasbeencorrelatedwithmyelinandmyelinformation,andadramaticdecreaseinCNPactivityisassociatedwithdemyelinatingdiseasessuchasmultiplesclerosis(Sprinkle,1989).Thisenzymeiscomposedoftwoproteins,CNP1(46kD)andCNP2(48kD)(Sprinkle,1989;Sprinkleetal.,1987).AlthoughtheratioofCNP1/CNP2mayvaryfromspeciestospecies,theirsharedprimarysequenceisconservedphyIogenetically.CNPhasrecentlybeenlocalizedtohumanchromosome17byamplificationofsomaticcellhybridDNAusingthepolymerasechainreaction(PCR)andbySouthernblottingofHindIllgenomicDNAdigests(Sprinkleetal.,1991).Sinceanti-CNPreactswithahighlyconservedregionoftheenzyme,itcanbeconsideredaspan-anti-CNP(Sprinkleetal.,1987).Anti-CNPcanbeusedasamarkertoidentifySchwanncellsandoligodendrocytesincellcuItureandintissuesections,aswellastolocalizeCNPincellmembranefractions.AsCNPisexpressedrelativelyearlyinpostnataldevelopment,anti-CNPisespeciallyusefulfortheearlyidentificationofoligodendrocytes. |