title: Dephosphorylation of the hepatic insulin receptor: absence of intrinsic phosphatase activity in purified receptors.
abstract: We have compared here the reversibility of phosphorylation of insulin receptors either partially purified by lectin chromatography, or highly purified by specific immunoprecipitation with anti-receptor antibodies. We found that the beta subunit of partially purified insulin receptors was rapidly dephosphorylated (t 1/2 = 15 min). In contrast, the level of phosphorylation of immunoprecipitated receptors remained unchanged for up to 4 hours at 37 degrees C. However, cytosolic phosphatases, which are inhibited by vanadate, were able to induce a complete dephosphorylation of immunoprecipitated receptors. These results show that 1. phosphorylation of insulin receptors is reversible; and 2. no phosphatase activity is contained in the insulin receptor structure itself.
mesh_terms: D000818:Animals; D011232:Chemical Precipitation; D003600:Cytosol / Q000201:enzymology; D007120:Immunochemistry; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism*; D013552:Swine
chemical_list: D011972:Receptor, Insulin; D010749:Phosphoprotein Phosphatases