Insulin regulation of the two glucose transporters in 3T3-L1 adipocytes

• Published in: The Journal of biological chemistry Vol. 265; no. 23; pp. 13800 - 13808
• Main Authors: CALDERHEAD, D. M, KITAGAWA, K, TANNER, L. I, HOLMAN, G. D, LIENHARD, G. E
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 15-08-1990
• Subjects: Adipose Tissue - cytology; Adipose Tissue - drug effects; Adipose Tissue - metabolism; Affinity Labels - metabolism; Animals; Biological and medical sciences; Cell Differentiation; Cell Membrane - metabolism; Cell physiology; Cells, Cultured; Cytoplasmic Granules - metabolism; Cytoplasmic Granules - ultrastructure; Deoxy Sugars - metabolism; Deoxyglucose - metabolism; Fundamental and applied biological sciences. Psychology; glucose transporter; insulin; Insulin - pharmacology; Intracellular Membranes - metabolism; Kinetics; Membrane and intracellular transports; Mice; Microscopy, Electron; Molecular and cellular biology; Molecular Weight; Monosaccharide Transport Proteins - isolation & purification; Monosaccharide Transport Proteins - metabolism; Adipocyte; Cell culture; Rodentia; 3T3-Cell line; Glucose; Photoaffinity labelling; Insulin; Membrane translocation; Vertebrata; Mammalia; Mouse; Hormonal regulation; Immunoblotting assay; Carrier protein; Quantitative analysis
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)77419-X

The amounts of the brain type and muscle type glucose transporters (designated Glut 1 and 4, respectively) in 3T3-L1 adipocytes
have been determined by quantitative immunoblotting with antibodies against their carboxyl-terminal peptides. There are about
950,000 and 280,000 copies of Glut 1 and 4, respectively, per cell. Insulin caused the translocation of both types of transporters
from an intracellular location to the plasma membrane. The insulin-elicited increase in cell surface transporters was assessed
by labeling the surface transporters with a newly developed, membrane-impermeant, photoaffinity labeling reagent for glucose
transporters. The increases in Glut 1 and 4 averaged 6.5- and 17-fold, respectively, whereas there was a 21-fold in hexose
transport. These results indicate that the translocation of Glut 4 could largely account for the insulin effect on transport
rate, but only if the intrinsic activity of Glut 4 is much higher than that of Glut 1. The two transporters are colocalized
intracellularly: vesicles (average diameter 72 nm) isolated from the intracellular membranes by immunoadsorption with antibodies
against Glut 1 contained 95% of the Glut 4 and, conversely, vesicles isolated with antibodies against Glut 4 contained 85%
of the Glut 1.