Similarities between a phosphoprotein (pp60src) -associated protein kinase of Rous sarcoma virus and a cyclic adenosine 3':5'-monophosphate-independent protein kinase that phosphorylates pyruvate kinase type M2
Presek, P.; Glossmann, H.; Eigenbrodt, E.; Schoner, W.; Rübsamen, H.; Friis, R.R.; Bauer, H.
Cancer Research 40(5): 1733-1741
1980
ISSN/ISBN: 0008-5472 PMID: 6245802 Document Number: 162732
Pyruvate kinase isoenzyme type M2 (M2-PK) was partially purified from chicken embryo cells (CEC) by affinity chromatography on Sepharose-coupled inhibitor protein (MW 33,500) of M2-PK. Transformation by Rous sarcoma virus leads to a lower affinity for phosphoenolpyruvate, a high stimulaton by fructose 1,6-diphosphate and a rapid inactivation by MgATP which is abolished by fructose 1,6-diphosphate. These characteristic changes of M2-PK in Rous sarcoma virus-transformed CEC could be mimicked in vitro by adding to homogeneous M2-PK from chicken liver a partially purified cyclicAMP-independent protein kinase. This enzyme phosphorylates and inactivates M2-PK. A protein with a MW of 64,000 can be phosphorylated in immune complexes, formed with monospecific M2-PK antisera and extracts from Rous sarcoma virus-transformed CED, but not from nontransformed CEC. This phosphoprotein has the same electrophoretic mobility as does M2-PK. It is assumed that transformation of CEC by Rous sarcoma virus may affect the regulatory system of M2-PK which includes inhibitory proteins and a cAMP-independent protein kinase. The transforming gene src of Rous sarcoma virus is coding for a phosphoprotein, pp60src, which is associated with protein kinase activity. This pp60src kinase activity was copurifying on affinity columns with M2-PK, hexokinase and 3-phosphoglycerate kinase. Evidence is presented which suggests functional similarities between pp60src kinase and the protein kinase which participates in the M2-PK regulation. Neither protein kinase can be stimulated by cAMP; they use GTP and ATP as phosphate donors. Both are inhibited by P1,P5-di(adenosine-5')pentaphosphate and M2-PK inhibitor protein. The inhibition by fructose 1,6-diphosphate of both protein kinases is noncompetitive with respect to ATP.