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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Trichomonas vaginalis pyruvate kinase was purified over 1750 fold to a specific activity greater than 100 mumol min-1 (mg protein)-1. The enzyme is a tetramer of M(r) 266,000, consisting of subunits of M(r) 53,000 and 56,000 in equivalent amounts. Its activity was dependent on the presence of magnesium but was not stimulated by potassium or ammonium. The enzyme exhibited positive cooperativity towards phosphoenolpyruvate and was inhibited by inorganic phosphate, which increased the sigmoidicity of the saturation curve for phosphoenolpyruvate without affecting maximal activity. It was heterotropically stimulated by ribose 5-phosphate and glycerate 3-phosphate, not previously known to act on eukaryotic pyruvate kinases, but was unaffected by known effectors of most pyruvate kinases, including fructose 1,6-bisphosphate and fructose 2,6-bisphosphate.
Mol Biochem Parasitol 1992 Aug
PMID:Pyruvate kinase from Trichomonas vaginalis, an allosteric enzyme stimulated by ribose 5-phosphate and glycerate 3-phosphate. 151 29

The major DNA-binding protein, or infected-cell protein 8 (ICP8), encoded by herpes simplex virus can localize to the cell nucleus independently of other viral proteins. To define the nuclear localization signals within ICP8, we performed several forms of mutagenesis on the cloned ICP8 gene. Deletion analysis of the ICP8 gene showed that several portions of ICP8 are involved in its nuclear localization. To determine whether these regions were independent localization signals, we introduced various portions of the ICP8 gene into a series of cassette plasmids which allowed expression of fusion proteins containing pyruvate kinase, normally a cytoplasmic protein, fused to various portions of ICP8. These results showed that the carboxyl-terminal 28 residues are the only portion of ICP8 capable of targeting protein kinase into the nucleus. However, inclusion of certain additional regions of ICP8 into the fusion protein led to an inhibition of nuclear localization. Therefore, the carboxyl-terminal 28 residues of ICP8 can act independently as a nuclear localization signal, but certain conformational constraints or folding or assembly requirements in the remainder of the protein can affect the nuclear localization of the protein. Our results demonstrate that sequences distant from a nuclear localization signal can affect its ability to function. A set of fusion vectors has been isolated which should be of general use for making 5' or 3' fusions in any reading frame to rapidly map localization signals.
Mol Cell Biol 1992 Mar
PMID:Distal protein sequences can affect the function of a nuclear localization signal. 154 14

The proteins encoded by the oncogene v-src and its cellular counterpart c-src (designated generically here as pp60src) are tightly associated with both plasma membranes and intracellular membranes. This association is due in part to the amino-terminal myristylation of pp60src, but several lines of evidence suggest that amino-terminal portions of the protein itself are also involved. We now report that pp60src contains at least three domains which, in conjunction with myristylation, are capable of mediating attachment to membranes and determining subcellular localization. We identified these domains by fusing various portions of pp60src to pyruvate kinase, which is normally a cytoplasmic protein. Amino acids 1 to 14 of pp60src are sufficient to mediate both myristylation and the attachment of pyruvate kinase to cytoplasmic granules. In contrast, amino acids 38 to 111 mediate association with the plasma membrane and perinuclear membranes, whereas amino acids 204 to 259 mediate association primarily with perinuclear membranes. We conclude that pp60src contains independent domains that target the protein to distinctive subcellular locations and thus may facilitate diverse biological functions of the protein.
Mol Cell Biol 1990 Mar
PMID:The src protein contains multiple domains for specific attachment to membranes. 168 55

The regulation of glycolytic genes in response to carbon source in the yeast Saccharomyces cerevisiae has been studied. When the relative levels of each glycolytic mRNA were compared during exponential growth on glucose or lactate, the various glycolytic mRNAs were found to be induced to differing extents by glucose. No significant differences in the stabilities of the PFK2, PGK1, PYK1, or PDC1 mRNAs during growth on glucose or lactate were observed. PYK::lacZ and PGK::lacZ fusions were integrated independently into the yeast genome at the ura3 locus. The manner in which these fusions were differentially regulated in response to carbon source was similar to that of their respective wild-type loci. Therefore, the regulation of glycolytic mRNA levels is mediated at the transcriptional level. When the mRNAs are ordered with respect to the glycolytic pathway, two peaks of maximal induction are observed at phosphofructokinase and pyruvate kinase. These enzymes (i) catalyze the two essentially irreversible steps on the pathway, (ii) are the two glycolytic enzymes that are circumvented during gluconeogenesis and hence are specific to glycolysis, and (iii) are encoded by mRNAs that we have shown previously to be coregulated at the translational level in S. cerevisiae (P. A. Moore, A. J. Bettany, and A. J. P. Brown, NATO ASI Ser. Ser. H Cell Biol. 49:421-432, 1990). This differential regulation of glycolytic mRNA levels might therefore have a significant influence upon glycolytic flux in S. cerevisiae.
Mol Cell Biol 1991 Oct
PMID:Yeast glycolytic mRNAs are differentially regulated. 192 48

Leishmania major promastigotes were grown to late log phase, washed and resuspended in Hanks' balanced salt solution, and incubated with glucose at various pO2s in the presence of 5% CO2. Samples were taken at times from 0-40 min and assayed for fructose 2,6-bisphosphate (Fru(2,6)P2), glucose-6-phosphate (G6P), fructose-6-phosphate (F6P), phospho(enol)pyruvate (PEP), and ATP. At 95% O2 ATP remained constant throughout the incubation. It did not decrease significantly at 10% O2, but decreased by about 20% and 30% at 6% and 0% O2, respectively. At 95% O2, Fru(2,6)P2 increased about 15-fold within 5 min after the addition of glucose and remained at this high level. At 10%, 6%, and 0% O2 Fru(2,6)P2 rose about 5-fold within 5 min and then declined slightly during the remainder of the incubation. G6P increased from about 0.5 to 12 nmol (mg protein)-1 at 5 min in cells incubated under 95% O2 and then declined to about 5 nmol (mg protein)-1. It increased to about 8 nmol (mg protein)-1 at 5 min and then declined slightly in cells incubated under 10% O2. F6P levels were approximately one-eighth of G6P levels under all conditions, suggesting that phosphohexoseisomerase was not subject to regulation. PEP levels were initially high, but at 95% O2 there was a 50% drop in PEP at 5 min, while at 10%, 6%, and 0% O2 there was less of a decline. The observation that the rise in Fru(2,6)P2 levels at 10%, 6%, or 0% O2 is the same at 5 min and less than the rise at 95% O2 supports the presence of a low affinity oxygen sensor. The different time course of changes in G6P, F6P, and PEP levels suggests that in addition to an activation of pyruvate kinase by Fru(2,6)P2, other regulatory events are also operative at low pO2.
Mol Biochem Parasitol 1991 Aug
PMID:Changes in intracellular levels of fructose 2,6-bisphosphate and several glycolytic intermediates in Leishmania major promastigotes as a function of pO2. 194 14

The activities of hexokinase (ATP:hexose-6-phosphate transferase, E.C. 2.7.1.1), phosphofructokinase (ATP:fructose-6-phosphate 1-phosphotransferase, E.C.2.7.1.11) and pyruvate kinase (ATP:pyruvate transferase, E.C. 2.7.1.40), and their kinetic behaviour in two morphological forms of Trypanosoma cruzi (epimastigotes and metacyclic trypomastigotes) have been studied. The kinetic responses of the three enzymes to their respective substrates were normalized to hyperbolic forms on a velocity versus substrate concentration plots. Hexokinase and phosphofructokinase showed a higher activity in epimastigotes than in metacyclics, whereas pyruvate kinase had similar activity in both forms of the parasite. The specific activity of hexokinase from epimastigotes was 102.00 mUnits/mg of protein and the apparent Km value for glucose was 35.4 microM. Metacyclic forms showed a specific activity of 55.25 mUnits/mg and a Km value of 46.3 microM. The kinetic parameters (specific activity and Km for fructose 6-phosphate) of phosphofructokinase for epimastigotes were 42.60 mUnits/mg and 0.31 mM and for metacyclics 13.97 mUnits/mg and 0.16 mM, respectively. On the contrary, pyruvate kinase in both forms of T. cruzi did not show significant differences in its kinetic parameters. The specific activity in epimastigotes was 37.00 mUnits/mg and the Km for phosphoenolpyruvate was 0.47 mM, whereas in metacyclics these values were 42.94 mUnits/mg and 0.46 mM, respectively. The results presented in this work, clearly demonstrate a quantitative change in the glycolytic pathway of both culture forms of T. cruzi.
Mol Cell Biochem 1990 Apr 18
PMID:Differential energetic metabolism during Trypanosoma cruzi differentiation. II. Hexokinase, phosphofructokinase and pyruvate kinase. 214 68

An inverse relationship between 2,3-bisphosphoglycerate levels and the ratio calculated from pyruvate kinase and bisphosphoglycerate mutase activities has been observed in red populations of rats during animal development. Counter-current distribution in aqueous two-phase systems of these cells populations shows a displacement of distribution profiles towards the high-numbered cavities of the rotor as animal ages. Heterogeneity of cells after distribution is only observed during the switching process from fetal to adult red cells taking place along the postnatal stage of development. Values for the pyruvate kinase/bisphosphoglycerate mutase ratio in these fractions suggest the separation of fetal (liver) from adult (bone marrow) red cells.
Mol Cell Biochem 1990 Apr 18
PMID:Fractionation in two-phase systems of red cells during rat development: changes in pyruvate kinase and bisphosphoglycerate mutase activities in relation to red cell switching. 216 31

In contrast to the species with erythrocytes of high 2,3-bisphosphoglycerate content, in the sheep the concentration of 2,3-bisphosphoglycerate decreases during maturation of reticulocytes. The decrease can be explained by the drop of the phosphofructokinase/pyruvate kinase and 2,3-bisphosphoglycerate synthase/2,3-bisphosphoglycerate phosphatase activity ratios that result from the decline of phosphofructokinase, pyruvate kinase, phosphoglycerate mutase and the bifunctional enzyme 2,3-bisphosphoglycerate synthase/phosphatase. The concentrations of fructose 2,6-bisphosphate and aldohexose 1,6-bisphosphates also decrease during sheep reticulocyte maturation in parallel to the 6-phosphofructo 2-kinase and the glucose 1,6-bisphosphate synthase activities.
Mol Cell Biochem 1990 Dec 03
PMID:2,3-Bisphosphoglycerate, fructose, 2,6-bisphosphate and glucose 1,6-bisphosphate during maturation of reticulocytes with low 2,3-bisphosphoglycerate content. 217 36

Polymerase basic protein 1 (PB1) of influenza virus (A/WSN/33), when expressed from cloned cDNA in the absence of other viral proteins, accumulates in the nucleus. We have examined the location and nature of the nuclear localization signal of PB1 by using deletion mutants and chimeric constructions with chicken muscle pyruvate kinase, a cytoplasmic protein. Our studies showed some novel features of the nuclear localization signal of PB1. The signal was present internally within residues 180 to 252 of PB1. Moreover, unlike most nuclear localization signals, it was not a single stretch of contiguous amino acids. Instead, it possessed two discontinuous regions separated by an intervening sequence which could be deleted without affecting its nuclear localization property. On the other hand, deletion of either of the two signal regions rendered the protein cytoplasmic, indicating that the function of both regions is required for nuclear localization and that one region alone is not sufficient. Both of these signal regions contained short stretches of basic residues. Possible ways by which this novel bipartite signal can function in nuclear localization are discussed.
Mol Cell Biol 1990 Aug
PMID:Function of two discrete regions is required for nuclear localization of polymerase basic protein 1 of A/WSN/33 influenza virus (H1 N1). 219 48

A cDNA for the gene that encodes a human cytosolic thyroid hormone binding protein (p58) recently has been isolated and sequenced. Analysis of the p58 sequence indicates that it is identical to the subunit of pyruvate kinase, subtype M2. By in situ hybridization, the gene for p58 was mapped to 15q24-25. This localization shows that the p58 gene is not linked to the L-type of pyruvate kinase, which is located on chromosome 1. The p58 gene was found to be activated in several forms of cancer. Current localization will permit us to assess the effect of alterations involving chromosome 15 on the structure and activity of the p58 gene in neoplasms or chromosome syndromes.
Somat Cell Mol Genet 1990 Nov
PMID:Chromosomal localization of the gene for a human cytosolic thyroid hormone binding protein homologous to the subunit of pyruvate kinase, subtype M2. 226 32


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