简介：Glucosetransporter4(GLUT4)isresponsibleforinsulin-stimulatedglucosetransportingintotheinsulin-sensitivefatandmusclecells.ThedynamicsofGLUT4storagevesicles(GSVs)remainstobeexploredanditisunclearhowGSVsarearrangedbasedontheirmobility.Weexaminedthisissuein3T3-L1cellsviainvestigatingthethree-dimensionalmobilityofsingleGSVlabeledwithEGFP-fusedGLUT4.Athinlayerofcytosolrightadjacenttotheplasmamembranewasilluminatedandsuccessivelyimagedat5Hzunderatotalinternalreflectionfluorescencemicroscopewithapenetrationdepthof136nm.Employingsingleparticletracking,thethree-dimensionalsubpixeldisplacementofsingleGSVwastrackedataspatialprecisionof22nm.Boththemeansquaredisplacementandthediffusioncoefficientwerecalculatedforeachvesicle.Trackingresultsrevealedthatvesiclesmovedasifrestrictedwithinacagethathasameanradiusof160nm,suggestingthepresenceofsomeintracellulartetheringmatrix.ByconstructingthehistogramofthediffusioncoefficientsofGSVs,weobservedasmoothdistributioninsteadoftheexistenceofdistinctgroups.TheresultindicatesthatGSVsaredynamicallyretainedinacontinuousandwiderangeofmobilityratherthanintoseparateclasses.