Insulin rapidly stimulates tyrosine phosphorylation of a Mr-185,000 protein in intact cells

Phosphotyrosine-containing proteins are minor components of normal cells which appear to be associated primarily with the regulation of cellular metabolism and growth. The insulin receptor is a tyrosine-specific protein kinase, and one of the earliest detectable responses to insulin binding is activation of this kinase and autophosphorylation of its beta-subunit. Tyrosine autophosphorylation activates the phosphotransferase in the beta-subunit and increases its reactivity toward tyrosine phosphorylation of other substrates. When incubated in vitro with [gamma-32P]ATP and insulin, the purified insulin receptor phosphorylates various proteins on their tyrosine residues. However, so far no proteins other than the insulin receptor have been identified as undergoing tyrosine phosphorylation in response to insulin in an intact cell. Here, using anti-phosphotyrosine antibodies, we have identified a novel phosphotyrosine-containing protein of relative molecular mass (Mr) 185,000 (pp185) which appears during the initial response of hepatoma cells to insulin binding. In contrast to the insulin receptor, pp185 does not adhere to wheat-germ agglutininagarose or bind to anti-insulin receptor antibodies. Phosphorylation of pp185 is maximal within seconds after exposure of the cells to insulin and exhibits a dose-response curve similar to that of receptor autophosphorylation, suggesting that this protein represents the endogenous substrate for the insulin receptor kinase.     

Structures and moelcular motions in alkaline earth hexammines

The alkaline earth hexammines have novel structures and molecular motions. The ammonia molecules in these compounds adopt an entirely different geometry from that of normal ammonia. There are two motional transitions as the temperature is increased. The first transition is due to ammonia rotation, and the second results from ammonia diffusion.     

Synthesis of L-[3-2H,18O]glycerol and its incorporation into the 4-methyl-5-hydroxyethyl thiazole moiety of thiamine byEscherichia coli

Summary L-[3-²H,¹⁸O]glycerol was prepared and fed toEscherichia coli in order to determine the origin of the oxygen atom in the biosynthesized thiazole moiety of thiamine. Measurement by GC-MS of the isotope incorporation into the thiazole from this substrate confirmed that the 2 hydrogens and the oxygen on the C-3 carbon of glycerol are incorporated directly into the thiazole.     

The biogenesis of helminthosporal

Zusammenfassung Die Biogenese des Pilzstoffes Helminthosporal wurde untersucht, indem der Pilz bei Anwesenheit von Mevalonsäure, mit C₂ mit Kohlenstoff-14 markiert, gezüchtet wurde. Es wird gezeigt, dass das Dialdehyd aus einem tricyclischen Vorläufer durch oxidative Spaltung entsteht.     

Lysozyme activity in the plaice (Pleuronectes platessa L.)

Zusammenfassung Die Untersuchung der Lysozymverteilung im Gewebe des Knochenfischs,Pleuronectes platessa L., ergab, dass das Plasma-Lysozym von Leukozyten abstammt, das Hautschleim-Lysozym dagegen von spezifischen Epidermiszellen.