(1) In this study we have determined the distribution of various membrane proteins involved in insulin-activated glucose transport in T-tubules and in sarcolemma from rat skeletal muscle. Two independent experimental approaches were used to determine the presence of membrane proteins in T-tubules: (i) the purification of T-tubules free from sarcolemmal membranes by lectin agglutination, and (ii) T-tubule vesicle immunoadsorption. These methods confirmed that T-tubules from rat skeletal muscle were enriched with dihydropyridine receptors and tt28 protein and did not contain the sarcolemmal markers dystrophin or beta 1-integrin. Both types of experiments revealed an abundant content of GLUT4 glucose carriers, insulin receptors and SCAMPs (secretory carrier membrane proteins) in T-tubule membranes. (2) Acute administration in vivo of insulin caused an increased abundance of GLUT4 in T-tubules and sarcolemma. On the contrary, insulin led to a 50% reduction in insulin receptors present in T-tubules and in sarcolemma, demonstrating that insulin-induced insulin receptor internalization affects T-tubules in the muscle fibre. The alteration in the content of GLUT4 and insulin receptors in T-tubules was a consequence of insulin-induced redistribution of these proteins. SCAMPs also redistributed in muscle membranes in response to insulin. They were recruited by insulin from intracellular high-density fractions to intracellular lighter-density fractions and to the cell surface, showing a pattern of insulin-induced cellular redistribution distinct from those of GLUT4 and the insulin receptor. (3) In conclusion, the T-tubule is a cell-surface target for membrane proteins involved in recycling such as SCAMPs or for membrane proteins that acutely redistribute in response to insulin such as GLUT4 or insulin receptors.
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December 1995
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Research Article|
December 01 1995
The T-tubule is a cell-surface target for insulin-regulated recycling of membrane proteins in skeletal muscle Available to Purchase
P Muñoz;
P Muñoz
*Departament de Bioquímica i Fisiologia, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 645, 08028 Barcelona, Spain
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M Rosemblatt;
M Rosemblatt
‡Departmento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
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X Testar;
X Testar
*Departament de Bioquímica i Fisiologia, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 645, 08028 Barcelona, Spain
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M Palacín;
M Palacín
*Departament de Bioquímica i Fisiologia, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 645, 08028 Barcelona, Spain
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G Thoidis;
G Thoidis
†Deparment of Biochemistry, Boston University Medical School, 80 Concord St., Boston, MA, U.S.A.
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P F Pilch;
P F Pilch
†Deparment of Biochemistry, Boston University Medical School, 80 Concord St., Boston, MA, U.S.A.
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A Zorzano
A Zorzano
*Departament de Bioquímica i Fisiologia, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 645, 08028 Barcelona, Spain
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Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1995 The Biochemical Society, London
1995
Biochem J (1995) 312 (2): 393–400.
Citation
P Muñoz, M Rosemblatt, X Testar, M Palacín, G Thoidis, P F Pilch, A Zorzano; The T-tubule is a cell-surface target for insulin-regulated recycling of membrane proteins in skeletal muscle. Biochem J 1 December 1995; 312 (2): 393–400. doi: https://doi.org/10.1042/bj3120393
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