Multiple Intracellular Peptide Mediators of Insulin Action
This chapter discusses a cluster of insulin mediator peptides that duplicate in vitro the following insulin actions in the cell: (1) inhibit cyclic adenosine monophosphate (cAMP)dependent protein kinase, (2) stimulate pyruvate dehydrogenase (PDH) phosphatase, (3) inhibit hormone-stimulated adenylate cyclase, and (4) stimulate glycogen synthase phosphoprotein phosphatase. Also discussed is a post-insulin receptor defect in human leprechaun fibroblast cells that sheds light on the mechanism of action of insulin. Finally, the possible relationship between insulin receptor phosphorylation and mediator formation is considered. It is clear that several mediators of varying molecular size is formed from proteins in the cell membrane following insulin binding to the receptor and that these mediators carry out some of the actions of insulin constituting the pleiotypic program. A model of mediator formation similar to the pro-opiomelanocortin model of peptide hormone formation is proposed. A recent review of this topic has appeared.(1)
KeywordsInsulin Action Pyruvate Dehydrogenase Insulin Binding Multiple Mediator Mediator Formation
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