The insulin-elicited 60-kDa phosphotyrosine protein in rat adipocytes is associated with phosphatidylinositol 3-kinase

• Published in: The Journal of biological chemistry Vol. 268; no. 8; pp. 5921 - 5928
• Main Authors: Lavan, B.E, Lienhard, G.E
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 15-03-1993
• Subjects: 3T3 Cells; ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; adipocytes; Adipose Tissue - metabolism; Animals; association; Biological and medical sciences; Cell physiology; CELLULE; CELULAS; containing; ESTRUCTURA CELULAR; FOSFOLIPIDOS; FOSFOPROTEINAS; FOSFORILACION; Fundamental and applied biological sciences. Psychology; insulin; Insulin - metabolism; Insulin Receptor Substrate Proteins; INSULINA; INSULINE; Mice; Molecular and cellular biology; PHOSPHATIDE; phosphatidylinositol 3-kinase; Phosphatidylinositol 3-Kinases; PHOSPHOPROTEINE; Phosphoproteins - metabolism; PHOSPHORYLATION; Phosphotransferases - metabolism; Phosphotyrosine; PROTEINAS; PROTEINE; proteins; RAT; RATA; Rats; Rats, Sprague-Dawley; Signal transduction; stimulation; STRUCTURE CELLULAIRE; TEJIDO ADIPOSO; TIROSINA; TISSU ADIPEUX; TRANSFERASAS; TRANSFERASE; TYROSINE; Tyrosine - analogs & derivatives; Tyrosine - metabolism; Proteins; Signal transduction; Vertebrata; Mammalia; Rat; Enzyme; Rodentia; Molecular association; Phosphatidylinositol kinase; Insulin; Protein-tyrosine kinase
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)53408-6

Insulin stimulates the tyrosine phosphorylation of a 60-kDa protein (pp60) in rat adipocytes. After insulin treatment of these cells, pp60, as well as the 160-kDa insulin receptor substrate-1 (IRS-1), were found to be associated with the enzyme phosphatidylinositol 3-kinase (PtdIns-3-kinase) in separate complexes. By contrast, pp60 was not detected in insulin-treated mouse 3T3-L1 adipocytes, which contain abundant IRS-1. PtdIns-3-kinase complex. The pp60.PtdIns 3-kinase complex was located in both the soluble and membrane fractions of the rat adipocytes. Fusion proteins containing the isolated src homology 2 domains from the 85-kDa subunit of PtdIns-3-kinase bound to pp60 in lysates of insulin-treated rat adipocytes. This finding indicates that the most likely mode of association of pp60 with PtdIns-3-kinase is through binding of phosphotyrosine residues in pp60 to these domains. By immunoaffinity chromatography on a monoclonal antibody against phosphotyrosine, pp60 was purified in high percentage yield from insulin-stimulated rat adipocytes, but the low amount of the protein obtained (about 3 ng from the adipocytes of one rat) precluded sequence analysis