Insulin, oxytocin, and vasopressin stimulate protein kinase C activity in adipocyte plasma membranes

J. J. Egan, J. Saltis, S. A. Wek, Ian Simpson, C. Londos

Research output: Contribution to journalArticle

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Abstract

Incubation of isolated rat adipocytes with insulin, vasopressin, or oxytocin increased plasma membrane-bound protein kinase C (PKC) activity by 100-400%. PKC activity was assayed by a procedure that is virtually background-free, thus permitting assay of protein kinase activity in highly diluted samples of solubilized membranes. Hormone-dependent increases in PKC activity were limited to plasma membranes. Stimulation of the kinase was half-maximal with 70 pM insulin, and the hormone effect was rapid. Oxytocin and vasopressin produced effects on PKC similar to insulin, but the magnitude of the vasopressin stimulation exhibited seasonal variations. Treatment of cells with phorbol 12-myristate 13-acetate (PMA) resulted in a loss of PKC activity from the cytosol and a gain in plasma membrane activity, indicative of translocation of the enzyme. With activity measurements it was not possible to determine if insulin stimulated a translocation of the kinase. However, Western blot analysis of plasma membranes with polyclonal antibodies directed against PKC suggest that at least some of the insulin-stimulated PKC activity resulted from enzyme translocation.

Original languageEnglish (US)
Pages (from-to)1052-1056
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume87
Issue number3
DOIs
StatePublished - Jan 1 1990

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Oxytocin
Vasopressins
Adipocytes
Protein Kinase C
Cell Membrane
Insulin
Phosphotransferases
Hormones
Enzymes
Cytosol
Protein Kinases
Blood Proteins
Membrane Proteins
Acetates
Western Blotting
Membranes
Antibodies

All Science Journal Classification (ASJC) codes

  • General

Cite this

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title = "Insulin, oxytocin, and vasopressin stimulate protein kinase C activity in adipocyte plasma membranes",
abstract = "Incubation of isolated rat adipocytes with insulin, vasopressin, or oxytocin increased plasma membrane-bound protein kinase C (PKC) activity by 100-400{\%}. PKC activity was assayed by a procedure that is virtually background-free, thus permitting assay of protein kinase activity in highly diluted samples of solubilized membranes. Hormone-dependent increases in PKC activity were limited to plasma membranes. Stimulation of the kinase was half-maximal with 70 pM insulin, and the hormone effect was rapid. Oxytocin and vasopressin produced effects on PKC similar to insulin, but the magnitude of the vasopressin stimulation exhibited seasonal variations. Treatment of cells with phorbol 12-myristate 13-acetate (PMA) resulted in a loss of PKC activity from the cytosol and a gain in plasma membrane activity, indicative of translocation of the enzyme. With activity measurements it was not possible to determine if insulin stimulated a translocation of the kinase. However, Western blot analysis of plasma membranes with polyclonal antibodies directed against PKC suggest that at least some of the insulin-stimulated PKC activity resulted from enzyme translocation.",
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Insulin, oxytocin, and vasopressin stimulate protein kinase C activity in adipocyte plasma membranes. / Egan, J. J.; Saltis, J.; Wek, S. A.; Simpson, Ian; Londos, C.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 87, No. 3, 01.01.1990, p. 1052-1056.

Research output: Contribution to journalArticle

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AU - Londos, C.

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