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Biochem Biophys Res Commun. 1998 Feb 13;243(2):509-13.

Protein kinase C modulates the insulin-stimulated increase in Akt1 and Akt3 activity in 3T3-L1 adipocytes.

Author information

1
Department of Molecular Pharmacology, Stanford University School of Medicine, California 94305, USA.

Abstract

In the present studies, we have compared the properties of two members of the Akt family of ser/thr kinases, Akt1 and Akt3. First, we demonstrate that both 3T3-L1 fibroblasts and adipocytes express Akt3 mRNA by RT-PCR and sequencing of the resultant PCR product. Second, we show that insulin stimulates the enzymatic activity of Akt1 and Akt3 15- and 7-fold, respectively. We then investigated the ability of protein kinase C to regulate Akt1 and 3. Neither enzyme was activated by stimulation of protein kinase C, however, the insulin-stimulated increases in activity of both isozymes were found to be comparably inhibited by prior protein kinase C activation. Since this inhibition could have resulted from an interaction of the pleckstrin homology domain of the Akt with protein kinase C, we also examined the ability of a mutant Akt1 lacking this domain to be regulated by this enzyme. The insulin-stimulated increase in enzymatic activity of this mutant Akt was regulated by PKC activation like the wild type enzyme. These results indicate that Akt1 and 3 are similarly stimulated by insulin and this stimulation is inhibited by prior activation of protein kinase C through a mechanism that is independent of the presence of the pleckstrin homology domain.

PMID:
9480839
DOI:
10.1006/bbrc.1998.8134
[Indexed for MEDLINE]

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