Tyrosine phosphorylation of Munc18c on residue 521 abrogates binding to Syntaxin 4

Veronica Aran, Nia J Bryant, Gwyn W Gould

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Background: Insulin stimulates exocytosis of GLUT4 from an intracellular store to the cell surface of fat and muscle cells. Fusion of GLUT4-containing vesicles with the plasma membrane requires the SNARE proteins Syntaxin 4, VAMP2 and the regulatory Sec1/Munc18 protein, Munc18c. Syntaxin 4 and Munc18c form a complex that is disrupted upon insulin treatment of adipocytes. Munc18c is tyrosine phosphorylated in response to insulin in these cells. Here, we directly test the hypothesis that tyrosine phosphorylation of Munc18c is responsible for the observed insulin-dependent abrogation of binding between Munc18c and Syntaxin 4. Results: We show that Munc18c is directly phosphorylated by recombinant insulin receptor tyrosine kinase in vitro. Using pull-down assays, we show that phosphorylation abrogates binding of Munc18c to both Syntaxin 4 and the v-SNARE VAMP2, as does the introduction of a phosphomimetic mutation into Munc18c (Y521E). Conclusion: Our data indicate that insulin-stimulated tyrosine phosphorylation of Munc18c impairs the ability of Munc18c to bind its cognate SNARE proteins, and may therefore represent a regulatory step in GLUT4 traffic.

Original languageEnglish
Article number19
Number of pages7
JournalBMC Biochemistry
Volume12
DOIs
Publication statusPublished - 6 May 2011

Fingerprint

Qa-SNARE Proteins
Phosphorylation
Tyrosine
SNARE Proteins
Insulin
Vesicle-Associated Membrane Protein 2
Adipocytes
Munc18 Proteins
Exocytosis
Cell membranes
Muscle Cells
Muscle
Assays
Fusion reactions
Fats
Cells
Cell Membrane
Mutation

Keywords

  • GLUT4
  • insulin
  • plasma membrane
  • Munc18c
  • syntaxin 4

Cite this

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abstract = "Background: Insulin stimulates exocytosis of GLUT4 from an intracellular store to the cell surface of fat and muscle cells. Fusion of GLUT4-containing vesicles with the plasma membrane requires the SNARE proteins Syntaxin 4, VAMP2 and the regulatory Sec1/Munc18 protein, Munc18c. Syntaxin 4 and Munc18c form a complex that is disrupted upon insulin treatment of adipocytes. Munc18c is tyrosine phosphorylated in response to insulin in these cells. Here, we directly test the hypothesis that tyrosine phosphorylation of Munc18c is responsible for the observed insulin-dependent abrogation of binding between Munc18c and Syntaxin 4. Results: We show that Munc18c is directly phosphorylated by recombinant insulin receptor tyrosine kinase in vitro. Using pull-down assays, we show that phosphorylation abrogates binding of Munc18c to both Syntaxin 4 and the v-SNARE VAMP2, as does the introduction of a phosphomimetic mutation into Munc18c (Y521E). Conclusion: Our data indicate that insulin-stimulated tyrosine phosphorylation of Munc18c impairs the ability of Munc18c to bind its cognate SNARE proteins, and may therefore represent a regulatory step in GLUT4 traffic.",
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Tyrosine phosphorylation of Munc18c on residue 521 abrogates binding to Syntaxin 4. / Aran, Veronica; Bryant, Nia J; Gould, Gwyn W.

In: BMC Biochemistry, Vol. 12, 19, 06.05.2011.

Research output: Contribution to journalArticle

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AU - Aran, Veronica

AU - Bryant, Nia J

AU - Gould, Gwyn W

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AB - Background: Insulin stimulates exocytosis of GLUT4 from an intracellular store to the cell surface of fat and muscle cells. Fusion of GLUT4-containing vesicles with the plasma membrane requires the SNARE proteins Syntaxin 4, VAMP2 and the regulatory Sec1/Munc18 protein, Munc18c. Syntaxin 4 and Munc18c form a complex that is disrupted upon insulin treatment of adipocytes. Munc18c is tyrosine phosphorylated in response to insulin in these cells. Here, we directly test the hypothesis that tyrosine phosphorylation of Munc18c is responsible for the observed insulin-dependent abrogation of binding between Munc18c and Syntaxin 4. Results: We show that Munc18c is directly phosphorylated by recombinant insulin receptor tyrosine kinase in vitro. Using pull-down assays, we show that phosphorylation abrogates binding of Munc18c to both Syntaxin 4 and the v-SNARE VAMP2, as does the introduction of a phosphomimetic mutation into Munc18c (Y521E). Conclusion: Our data indicate that insulin-stimulated tyrosine phosphorylation of Munc18c impairs the ability of Munc18c to bind its cognate SNARE proteins, and may therefore represent a regulatory step in GLUT4 traffic.

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