Molecular Cloning of pp120/ ECTO-ATPase, An Endogenous Substrate of the Insulin Receptor Kinase
In recent years, a great deal of attention has been devoted to dissecting intracellular pathways of insulin action following activation of the insulin receptor kinase (1). Several laboratories have reported the identification of protein substrates of the insulin receptor tyrosine kinase (2). Here, we review our studies of pp120/ecto-ATPase, a liver-specific glycoprotein of Mr-120,000 which was originally identified by us as a substrate of the insulin receptor tyrosine kinase in cell-free phosphorylation assays (3). Independently, other laboratories have identified the same protein as a hepatic enzyme capable of hydrolyzing extracellular ATP and GTP. Recently, cDNA and genomic cloning studies have contributed to elucidate the structure of this protein and to formulate hypotheses on its function. This chapter will focus on the potential role of pp120/ecto-ATPase in mediating actions of insulin in the liver.
KeywordsInsulin Receptor Insulin Receptor Tyrosine Kinase Hepatocyte Plasma Membrane Insulin Receptor Kinase Truncate Protein Product
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