A variety of studies indicate that protein kinase C might be involved in the insulin signalling cascade leading to translocation of the insulin-regulated glucose transporter GLUT4 from intracellular pools to the plasma membrane. Phospholemman is a plasma-membrane protein kinase C substrate whose phosphorylation is increased by insulin in intact muscle [Walaas, Czernik, Olstad, Sletten and Walaas (1994) Biochem. J. 304, 635-640]. The present study examined whether the inhibition of phospholemman phosphorylation modulates the effects of insulin on GLUT4 translocation. For this purpose, a synthetic peptide derived from the intracellular domain of phospholemman with the phosphorylatable serine residues replaced with alanine residues was prepared. This peptide was found to decrease the protein kinase C-catalysed phosphorylation of a synthetic phospholemman peptide in vitro. When introduced into streptolysin-O-permeabilized adipocytes, the peptide decreased the effects of insulin on both the phosphorylation of phospholemman and the recruitment of GLUT4 to the plasma membrane. Similarly, the internalization of phospholemman antibodies, which also decreased the protein kinase C-mediated phosphorylation of the synthetic phospholemman peptide in vitro, decreased the effect of insulin on GLUT4 translocation in the adipocytes. The results suggest that phosphorylation of the intracellular domain of phospholemman might be involved in modulating the insulin-induced translocation of GLUT4 to the plasma membrane.
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Research Article|
September 24 1999
Inhibition of insulin-stimulated phosphorylation of the intracellular domain of phospholemman decreases insulin-dependent GLUT4 translocation in streptolysin-O-permeabilized adipocytes
Otto WALAAS;
Otto WALAAS
1
*Neurochemical Laboratory, University of Oslo, P.O. Box 1115-Blindern, 0317 Oslo, Norway
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Robert S. HORN;
Robert S. HORN
†Institute of Medical Biochemistry, University of Oslo, P.O. Box 1112-Blindern, 0317 Oslo, Norway
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S. Ivar WALAAS
S. Ivar WALAAS
2
*Neurochemical Laboratory, University of Oslo, P.O. Box 1115-Blindern, 0317 Oslo, Norway
2To whom correspondence should be addressed (e-mail ivar.walaas@basalmed.uio.no).
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Publisher: Portland Press Ltd
Received:
January 22 1999
Revision Received:
June 28 1999
Accepted:
July 15 1999
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1999
1999
Biochem J (1999) 343 (1): 151–157.
Article history
Received:
January 22 1999
Revision Received:
June 28 1999
Accepted:
July 15 1999
Citation
Otto WALAAS, Robert S. HORN, S. Ivar WALAAS; Inhibition of insulin-stimulated phosphorylation of the intracellular domain of phospholemman decreases insulin-dependent GLUT4 translocation in streptolysin-O-permeabilized adipocytes. Biochem J 1 October 1999; 343 (1): 151–157. doi: https://doi.org/10.1042/bj3430151
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