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. |