Pyruvate kinase type M₂ is phosphorylated at tyrosine residues in cells transformed by Rous sarcoma virus

Abstract

Chicken embryo cells (CECs) contain pyruvate kinase (PK) type M~ (M2-PK). Transformation of CECs by Rous sarcoma virus (RSV) leads to a reduction in the affinity of PK for the substrate phosphoeno/pyruvate. In vitro, M2-PK can be phosphorylated at tyrosine residues by pp60 v-~, the transforming protein of RSV. To study tyrosine phosphorylation of M2-PK in intact RSV-transformed cells, the protein was immunoprecipitated from a2P-labeled normal and RSV-SR-Atransformed CECs. Phosphoamino acid analysis of immunoprecipitated Mz-PK revealed that M2-PK of both normal and transformed CECs contained phosphoserine and small amounts of phosphothreonine. Only Mz-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 Mz-PK, but there is no direct evidence that they are caused by post-translational modification of the enzyme.

Pharmacologic Activation of PKM2 Slows Lung Tumor Xenograft Growth

“…These findings indicate that control of glycolytic flux through PKM2 activation/inactivation may be important for tumor growth in some indications. Cancer cells inactivate PKM2 through multiple mechanisms, including oncoprotein binding (14,15), tyrosine phosphorylation (16)(17)(18), lysine acetylation (19), cysteine oxidation (20), and prolyl hydroxylation (21). In each case, decreased PKM2 activity correlates with increased tumorigenicity.…”

Hypoxic Response of Synaptosomal Proteins in Term Guinea Pig Fetuses

“…Further attempts to identify spots involved in hypoxia-induced responses must be confirmed also by direct microanalytical characterization; experiments are in progress to identify spots using protein sequencing and/or mass spectrometric techniques. Several observations can be positively interpreted: (a) as expected, proteins identified by gel comparison with a human 2-D reference map involved "housekeeping" and/or well conserved protein species; (b) most identified spots positive to anti-PY antibodies resulted as either known tyrosinephosphorylated proteins, e.g., tubulin (MacRae, 1997), HSC70 (Egerton et al, 1996), and pyruvate kinase (Presek et al, 1988), or tyrosine-phosphorylation sites containing proteins, as predicted by the ScanPROSITE algorithm (see Materials and Methods); and (c) as expected, several identified proteins containing no tyrosinephosphorylation site resulted as nonimmunoreactive spots (e.g., NADH-ubiquinone dehydrogenase 24-kDa subunit).…”

Antigen Presentation by Dendritic Cells in Tumors Is Disrupted by Altered Metabolism that Involves Pyruvate Kinase M2 and Its Interaction with SOCS3

“…Other studies have shown that M2-PK activity in tumor cells is also regulated by the direct interaction of M2-PK with several oncoproteins. The transforming factor of Rous sarcoma virus, pp60v-src kinase, has tyrosine kinase-specific activity and phosphorylates M2-PK at a tyrosine residue to reduce M2-PK activity (23,36). The serine/threonine kinase A-Raf directly binds to M2-PK to regulate the pyruvate kinase (25).…”