Temporal separation of insulin-stimulated GLUT4/IRAP vesicle plasma membrane docking and fusion in 3T3L1 adipocytes.
Examination of the time and temperature dependence of insulin-stimulated GLUT4/IRAP-containing vesicle trafficking demonstrated an approximate 7-fold increase in the half-time for plasma membrane translocation at 23 degrees C (t((1)/(2)) = approximately 30 min) compared with 37 degrees C (t((1)/(2)) = approximately 4 min) without a significant change in the extent of either GLUT4 or IRAP translocation. Localization of the endogenous GLUT4 and expressed GLUT4-enhanced green fluorescent protein fusion protein in intact 3T3L1 adipocytes demonstrated that at 23 degrees C there was a time-dependent accumulation of discrete GLUT4-containing vesicles adjacent to the inner face of the cell surface membrane but that was not contiguous and/or physically incorporated into the plasma membrane. Together, these data demonstrate that the temperature-dependent decrease in the rate of GLUT4 and IRAP translocation results from a reduction in GLUT4/IRAP-containing vesicle fusion and not trafficking or docking to the plasma membrane.
Elmendorf
J S
JS
Department of Physiology, The University of Iowa, Iowa City, Iowa 52242, USA.
Boeglin
D J
DJ
Pessin
J E
JE
D016475:3T3 Cells; D017667:Adipocytes / Q000737:chemistry / Q000378:metabolism*; D000626:Aminopeptidases / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D051275:Glucose Transporter Type 4; D049452:Green Fluorescent Proteins; D007328:Insulin / Q000494:pharmacology*; D008164:Luminescent Proteins / Q000378:metabolism; D008561:Membrane Fusion; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D009124:Muscle Proteins; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013696:Temperature
D051275:Glucose Transporter Type 4; D007328:Insulin; D008164:Luminescent Proteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D011993:Recombinant Fusion Proteins; C495693:Slc2a4 protein, mouse; D049452:Green Fluorescent Proteins; D000626:Aminopeptidases