UniProtSummary | FUNCTION:TheclassicgroupofMBPisoforms(isoform4-isoform14)arewithPLPthemostabundantproteincomponentsofthemyelinmembraneintheCNS.TheyhavearoleinbothitsformationandstABIlization.Thesmallerisoformsmighthaveanimportantroleinremyelinationofdenudedaxonsinmultiplesclerosis.Thenon-classicgroupofMBPisoforms(isoform1-isoform3/Golli-MBPs)maypreferentiallyhavearoleintheearlydevelopingbrainlongbeforemyelination,maybeascomponentsoftranscriptionalcomplexes,andmayalsobeinvolvedinsignalingpathwaysinT-cellsandneuralcells.Differentialsplicingeventscombinedtooptionalpost-translationalmodificationsgiveawidespectrumofisomers,eachofthemhavingmaybeaspecializedfunction.InducesT-cellproliferation.
SIZE:304aminoacids;33117Da
SUBUNIT:Homodimer;isoform3existsasahomodimer.
SUBCELLULARLOCATION:Myelinmembrane;Peripheralmembraneprotein;Cytoplasmicside.Note=Cytoplasmicsideofmyelin.
TISSUESPECIFICITY:MBPisoformsarefoundinboththecentralandtheperipheralnervoussystem,whereasGolli-MBPisoformsareexpressedinfetalthymus,spleenandspinalcord,aswellasincelllinesderivedfromtheimmunesystem.DEVELOPMENTALSTAGE:Expressionturnsonabruptlyinfetusof14to16weeks.Evensmallerisoformsseemtobeproducedduringembryogenesis,someofthesepersistingintheadult.ExpressionofisoformMBP2ismoreevidentat16weeksanditsrelativeproportiondeclinedthereafter.
PTM:SeveralchargeisomersofMBP;C1(themostcationic,leastmodified,andmostabundantform),C2,C3,C4,C5,C6,C7,C8-AandC8-B(theleastcationicform);areproducedasaresultofoptionalPTM,suchasphosphorylation,deamidationofglutamineorasparagine,argininecitrullinationandmethylation.C8-AandC8-BcontaineachtwomassisoformstermedC8-A(H),C8-A(L),C8-B(H)andC8-B(L),(H)standingforhigherand(L)forlowermolecularweight.C3,C4andC5arephosphorylated.Theratioofmethylatedarginineresiduesdecreasesinaging,makingtheproteinmorecationic.&TheN-terminalalanineisacetylated(isoform3,isoform4,isoform5andisoform6).&Arg-241wasfoundtobe6%monomethylatedand60%symmetricallydimethylated.
DISEASE:Thereductioninthesurfacechargeofcitrullinatedand/ormethylatedMBPcouldresultinaweakenedattachmenttothemyelinmembrane.Thismechanismcouldbeoperativeindemyelinatingdiseasessuchaschronicalmultiplesclerosis(MS),andfulminatingMS(Marburgdisease).
SIMILARITY:Belongstothemyelinbasicproteinfamily. |