Insulin-regulatable phosphoproteins in 3T3-L1 adipocytes form detergent-insoluble complexes not associated with caveolin

Electrophoresis
M M HillD E James

Abstract

Whole body glucose homeostasis is dependent on the action of insulin. In muscle and adipose tissues, insulin stimulates glucose uptake by inducing the translocation of vesicles containing the glucose transporter GLUT4 to the cell surface. While the mechanisms of insulin-regulated GLUT4 translocation are not fully understood, some signaling intermediates have been implicated in this process. Interestingly, some of these intermediates, including IRS-1 and PI3K, have been localised to the same intracellular membrane fraction as the GLUT4 storage pool, designated here as the high-speed pellet (HSP) fraction. This raises the possibility that many of the downstream insulin signaling intermediates may be located within close proximity to intracellular GLUT4. The goal of this study was to test this hypothesis in 3T3-L1 adipocytes. A large proportion of adipocyte phosphoproteins co-fractionated in the HSP fraction. In an attempt to resolve insulin-regulatable phosphoproteins, we subjected 32P-labeled subcellular fractions to two-dimensional gel electrophoresis (2-DE). Insulin reproducibly stimulated the phosphorylation of 12 spots in the HSP fraction. Most of the HSP phosphoproteins were insoluble in the nonionic detergent Triton X-100,...Continue Reading

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Citations

Mar 14, 2000·Current Opinion in Cell Biology·J P WhiteheadD E James
Dec 14, 1999·Molecular and Cellular Biology·M Hashiramoto, D E James
Aug 18, 2004·Proceedings of the National Academy of Sciences of the United States of America·Jin OshikawaYoshihiro Ishikawa
Apr 20, 2005·Biology of the Cell·Anne-Marie Chambaut-Guérin, Jacques Pairault
Sep 1, 2004·Biochemical and Biophysical Research Communications·Alex MammenCheil Moon
Jul 15, 2004·The Journal of Biological Chemistry·Alejandro BalbisBarry I Posner
Apr 15, 2000·The Journal of Biological Chemistry·R C Hresko, M Mueckler
Dec 24, 2002·The Journal of Biological Chemistry·Satoshi ShigematsuJeffrey E Pessin
Oct 19, 1999·Molecular and Cellular Biology·M M HillS L Macaulay
Oct 3, 2002·The Journal of Biological Chemistry·Robert G PartonDavid E James

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