UniProtSummary | FUNCTION:Tubulinisthemajorconstituentofmicrotubules.ItbindstwomolesofGTP,oneatanexchangeablesiteonthebetachainandoneatanon-exchangeablesiteonthealpha-chain.TUBB3playsacriticalroleinproperaxonguidanceandmantainance. SUBUNITSTRUCTURE:Dimerofalphaandbetachains. SUBCELLULARLOCATION:Cytoplasm?Cytoskeleton. TISSUESPECIFICITY:Expressionisprimarilyrestrictedtocentralandperipheralnervoussystem.Greatlyincreasedexpressioninmostcanceroustissues. DOMAIN:ThehighlyacidicC-terminalregionmaybindcationssuchascalcium. PTM:SomeglutamateresiduesattheC-terminusarepolyglutamylated.Thismodificationoccursexclusivelyonglutamateresiduesandresultsinpolyglutamatechainsonthegamma-carboxylgroup.AlsomonoglycylatedbutnotpolyglycylatedduetotheabsenceoffunctionalTTLL10inhuman.Monoglycylationismainlylimitedtotubulinincorporatedintoaxonemes(ciliaandflagella)whereasglutamylationisprevalentinneuronalcells,centrioles,axonemes,andthemitoticspindle.Bothmodificationscancoexistonthesameproteinonadjacentresidues,andloweringglycylationlevelsincreasespolyglutamylation,andreciprocally.TheprecisefunctionofsuchmodificationsisstillunclearbuttheyregulatetheassemblyanddynamicsofaxonemalmicrotubulesProbable. PhosphorylatedonSer-172byCDK1duringthecellcycle,frommetaphasetotelophase,butnotininterphase.Thisphosphorylationinhibitstubulinincorporationintomicrotubules. INVOLVEMENTINDISEASE:DefectsinTUBB3arethecauseofcongenitalfibrosisofextraocularmusclestype3A(CFEOM3A)[MIM:600638].Acongenitalocularmotilitydisordermarkedbyrestrictiveophthalmoplegiaaffectingextraocularmusclesinnervatedbytheoculomotorand/ortrochlearnerves.Itisclinicallycharacterizedbyanchoringoftheeyesindownwardgaze,ptosis,andbackwardtiltofthehead.Congenitalfibrosisofextraocularmusclestype3presentsasanon-progressive,autosomaldominantdisorderwithvariableexpression.Patientsmaybebilaterallyorunilaterallyaffected,andtheiroculo-motilitydefectsrangefromcompleteophthalmoplegia(withtheeyesfixedinahypo-andexotropicposition),tomildasymptomaticrestrictionsofocularmovement.Ptosis,refractiveerror,amblyopia,andcompensatoryheadpositionsareassociatedwiththemoresevereformsofthedisorder.Insomecasestheocularphenotypeisaccompaniedbyadditionalfeaturesincludingdevelopmentaldelay,corpuscallosumagenesis,basalgangliadysmorphism,facialweakness,polyneuropathy. SEQUENCESIMILARITIES:Belongstothetubulinfamily.
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