3‐Mercaptopicolinic acid, a preferential inhibitor of the cytosolic phosphoenolpyruvate carboxykinase

Robinson, Brian H.; Oei, J.

doi:10.1016/0014-5793(75)80214-6

Cited by 49 publications

(20 citation statements)

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“…Fig. 1 and the differences between values in columns 2 and 3 of Table 2 show that the incorporation of radioactivity into glycogen was reduced by 3-mercaptopicolinate, an inhibitor of phosphoenolpyruvate carboxykinase (Ditullio et al, 1974;Goodman, 1975;Robinson and Oei, 1975). Incorporation rates showed a contribution of not more than 0.1% of the precursors to glycogen synthesis, i.e.…”

Section: Subcellular Location Of Phosphoenolpyruvate Carboxykinasementioning

confidence: 94%

“…This demonstrated that the incorporation of the radioactive label into the astroglial glycogen depended on the action of phosphoenolpyruvate carboxykinase and could not be attributed to a theoretical possible 14C exchange between pyruvate and phosphoenolpyruvate, catalyzed by pyruvate kinase. The incomplete inhibition of the incorporation can be explained by the observation that 3-mercaptopicolinate is a better inhibitor for the cytosolic isoenzyme of phosphoenolpyruvate carboxykinase than for the mitochondria1 isoform (Robinson and Oei, 1975), the isoenzyme present in the astroglial cells. Neither the mechanism by which 3-mercaptopicolinate inhibits phosphoenolpyruvate carboxykinase nor its stability inside the cell is known.…”

Section: Discussionmentioning

confidence: 99%

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Significant Amounts of Glycogen are Synthesized from 3‐Carbon Compounds in Astroglial Primary Cultures from Mice with Participation of the Mitochondrial Phosphoenolpyruvate Carboxykinase Isoenzyme

Schmoll

Führmann

Gebhardt

et al. 1995

European Journal of Biochemistry

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The incorporation was studied of the gluconeogenic substrates lactate, alanine, aspartate and glutamate into glycogen of astroglial primary cultures derived from mouse brain. The incorporation was inhibited by 3-mercaptopicolinate, an inhibitor of one of the characteristic gluconeogenic enzymes, phosphoenolpyruvate carboxykinase. Only the mitochondrial isoenzyme of phosphoenolpyruvate carboxykinase was detect,able in the astroglial primary cultures. After the incubation of glucose-starved cells with medium containing a mixture of [6-3H]glucose and [U-'4C]glucose, the newly synthesized glycogen showed a 3W 14C ratio which was approximately 15% less than the isotope ratio for the medium. The decrease of the isotope ratio was not significantly inhibited by 3-mercaptopicolinate, indicating a cycling of approximately 15% of the glucose to the level of the triose phosphates before its incorporation into astroglial glycogen. During the initial phase of glycogen resynthesis, the contribution of the gluconeogenic substrates appeared to be higher. This was in agreement with the accumulation of fructose 2,6-bisphosphate during refeeding. A participation of gluconeogenic substrates in glycogen metabolism was also detectable when the glycogen content was not changing significantly.

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Section: Subcellular Location Of Phosphoenolpyruvate Carboxykinasementioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Significant Amounts of Glycogen are Synthesized from 3‐Carbon Compounds in Astroglial Primary Cultures from Mice with Participation of the Mitochondrial Phosphoenolpyruvate Carboxykinase Isoenzyme

Schmoll

Führmann

Gebhardt

et al. 1995

European Journal of Biochemistry

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“…40) or NAD(P)-linked malic enzyme. Of these PEP carboxykinase plus pyruvate kinase is least likely because mercaptopicolinate, an inhibitor of PEP carboxykinase [95,96] has no effect on the oxidation of glutamine in the small intestine or in rat kidney tubules [97,98]. Watford et al [98] came to K90 the conclusion that the cytosolic NADP-linked malic enzyme was the most likely pathway.…”

Section: Glutamine As a Respiratory Fuelmentioning

confidence: 99%

Glutamine metabolism in the rat

Lund

1980

FEBS Letters

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“…2b). in contrast to parental OK wild-type cells [19], The expression of PEPCK activity in OKgng+ cells was assayed indirectly, using 3-MPA, a specific PEPCK inhibitor [21][22][23], 3-MPA completely inhibited growth of OKGng+ cul tures. indicating that the cells express PEPCK activity, and fully depend on metabolic flux through gluconeogenesis when cultured under essentially glucose-free conditions, and when the gluconeogenic substrates supplemented (lactate and pyruvate) enter the gluconeogenic pathway before the PEPCK step.…”

Section: Discussionmentioning

confidence: 99%

A Novel Gluconeogenic Strain of OK Cells with Metabolic Properties Different from Gluconeogenic LLC-PK<sub>1</sub> Cells

Gstraunthaler¹,

Thurner²,

Weirich‐Schwaiger³

et al. 1993

Cell Physiol Biochem

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By selective adaptation to glucose-free tissue culture conditions, a gluconeogenic substrain of the opossum kidney (OK) cell line, designated OK_gNg+, was established, analogous to the method recently employed for the isolation of gluconeogenic LLC-PK₁-FBPase+ cells [Gstraunthaler and Handler, Am J Physiol 1987;252:C232-C238]. OK_Gng+ cells express considerable amounts of fructose-1, 6-bisphosphatase activity, and metabolic flux through phosphoenolpyruvate carboxykinase (PEPCK), which is indicative for their gluconeogenic capacity, in contrast to OK wild-type cells. OK_gng+ cells also seem to exhibit a higher degree of differentiation indicated by an increased expression of γ-glutamyltranspeptidase activity. Karyotype analysis revealed that OK_gng+ cells are descendants of OK wild-type cells, exhibiting slight increases in tetraploidy. Remarkable differences between OK_gng+ and LLC-PK₁^-FBPase+ cells have been found in terms of substrate metabolism of the two gluconeogenic renal sub-strains. Cultures were incubated in culture medium containing either Na-L-lactate, Na-pyruvate or lactate/pyruvate mixtures (10:1, 5:5, 1:10) as main gluconeogenic substrates. OKg_gng+ cultures grew better in lactate than in pyruvate, whereas the opposite was observed with LLC-PK₁^-FBPase+ cells. This was further confirmed by the consumption rates of lactate and pyruvate by the substrains. When lactate or lactate/pyruvate were supplied, OKq_gng+ cells consumed lactate at much higher rates as compared to LLC-PK₁^-FBPase+ cultures. When pyruvate was added as the sole gluconeogenic substrate, pyruvate consumption rates by LLC-PK₁^-FBPase+ cells were linear over time, without considerable lactate production. However, pyruvate consumption by OK_gng+ cells was almost completed after 24-48 h, and resulted in an equimolar production and accumulation of lactate in the culture medium, respectively, which was consumed by the cells thereafter. In summary, a novel gluconeogenic strain of OK cells has been established (OK_gng+), as previously shown for gluconeogenic LLC-PK₁^-FBPase+ cells. Both cell strains, however, differ markedly in the metabolism of lactate and pyruvate, and thus obviously in the subcellular localization of PEPCK, in their regulation of gluconeogenesis by the intracellular NADH/NAD ratio, and/or in the rate of mitochondrial substrate fluxes and shuttle activities, respectively.

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3‐Mercaptopicolinic acid, a preferential inhibitor of the cytosolic phosphoenolpyruvate carboxykinase

Cited by 49 publications

References 10 publications

Significant Amounts of Glycogen are Synthesized from 3‐Carbon Compounds in Astroglial Primary Cultures from Mice with Participation of the Mitochondrial Phosphoenolpyruvate Carboxykinase Isoenzyme

Significant Amounts of Glycogen are Synthesized from 3‐Carbon Compounds in Astroglial Primary Cultures from Mice with Participation of the Mitochondrial Phosphoenolpyruvate Carboxykinase Isoenzyme

Glutamine metabolism in the rat

A Novel Gluconeogenic Strain of OK Cells with Metabolic Properties Different from Gluconeogenic LLC-PK<sub>1</sub> Cells

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