Pyruvate kinase type M2 is phosphorylated at tyrosine residues in cells transformed by Rous sarcoma virus.
Chicken embryo cells (CECs) contain pyruvate kinase (PK) type M2 (M2-PK). Transformation of CECs by Rous sarcoma virus (RSV) leads to a reduction in the affinity of PK for the substrate phosphoenolpyruvate. In vitro, M2-PK can be phosphorylated at tyrosine residues by pp60v-src, the transforming protein of RSV. To study tyrosine phosphorylation of M2-PK in intact RSV-transformed cells, the protein was immunoprecipitated from 32P-labeled normal and RSV-SR-A-transformed CECs. Phosphoamino acid analysis of immunoprecipitated M2-PK revealed that M2-PK of both normal and transformed CECs contained phosphoserine and small amounts of phosphothreonine. Only M2-PK of transformed CECs contained phosphotyrosine in addition. For enzyme kinetic studies M2-PK was partially purified by chromatography upon DEAE-Sephacel and hydroxyapatite. A decreased affinity for phosphoenolpyruvate was observed 3 h after the onset of transformation using the temperature-sensitive mutant of RSV, ts-NY 68. The kinetic changes were correlated with tyrosine phosphorylation of M2-PK, but there is no direct evidence that they are caused by post-translational modification of the enzyme.
Presek
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P
Rudolf Buchheim-Institut für Pharmakologie, Justus Liebig-Universität Giessen, FRG.
Reinacher
M
M
Eigenbrodt
E
E
D000818:Animals; D001358:Avian Sarcoma Viruses; D002472:Cell Transformation, Viral; D002642:Chick Embryo; D007163:Immunosorbent Techniques; D007700:Kinetics; D015688:Oncogene Protein pp60(v-src); D010728:Phosphoenolpyruvate / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D010769:Phosphothreonine / Q000378:metabolism; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; D011770:Pyruvate Kinase / Q000378:metabolism*; D012191:Retroviridae Proteins / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D012191:Retroviridae Proteins; D010769:Phosphothreonine; D010768:Phosphoserine; D019000:Phosphotyrosine; D014443:Tyrosine; D010728:Phosphoenolpyruvate; D011770:Pyruvate Kinase; D011505:Protein-Tyrosine Kinases; D015688:Oncogene Protein pp60(v-src)