Regulation of insulin receptor signaling by protein-tyrosine dephosphorylation.

Protein-tyrosine phosphatases (PTPases) that dephosphorylate the active (autophosphorylated) form of the insulin receptor and attenuate its tyrosine kinase activity play an essential regulatory role in signaling mediated by the insulin receptor. PTPases also modulate signaling through postreceptor pathways by catalyzing the dephosphorylation of cellular substrates of the insulin receptor kinase, such as IRS-1, or other tyrosine-phosphorylated proteins along the cellular cascade of insulin action. Recent studies have provided important data regarding PTPase(s) in insulin-responsive tissues that may regulate various components of the insulin action pathway. Further studies in this area will enhance our understanding of the mechanisms involved in insulin signaling and clarify the potential involvement of PTPases in the pathophysiology of insulin-resistant disease states.