The Regulation of Glycolysis and the Pentose Phosphate Pathway

Turner, John F.; Turner, Donella H.

doi:10.1016/b978-0-12-675411-7.50010-0

Cited by 93 publications

(79 citation statements)

References 127 publications

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“…SPS facilitates C removal from chloroplasts, helping to maintain a high photosynthetic rate. PK is crucial for glycolytic C flux to pyruvate (Copeland and Turner 1987, Plaxton et al 1993, Plaxton 1996. The relative expression levels of each mRNA were similar in leaves of different ages, except for the PEPC mRNA, which accumulated more strongly in leaves at late growth stages.…”

Section: Discussionmentioning

confidence: 85%

Developmental regulation of photosynthate distribution in leaves of rice

Shinano

Nakajima²,

Wasaki

et al. 2006

Photosynt.

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AbstractmRNA expression patterns of genes for metabolic key-enzymes (sucrose phosphate synthase [SPS], phosphoenolpyruvate carboxylase [PEPC], pyruvate kinase, ribulose 1,5-bisphosphate carboxylase/oxygenase, glutamine synthetase 1, and glutamine synthetase 2) were investigated in leaves of rice plants grown at two nitrogen (N) concentrations. The relative gene expression patterns were similar in all leaves except for 9 th leaf, in which mRNA levels were generally depressed.Though an increased N concentrations prolonged the expression period of each mRNA, it did not affect the relative expression intensity of any mRNA in a given leaf. SPS V max , SPS limiting activity, PEPC activity, and carbon flow were examined using 14 CO 2 . The ratio between PEPC activity and SPS V max was higher in leaves developed at the vegetative growth stage (vegetative leaves: 5 th and 7 th 1 leaf) than in leaves developed after the ear primordia formation stage (reproductive leaves: 9 th and flag leaf). PEPC activity and SPS V max decreased with declining leaf N concentration. The 14 C photosynthate distribution to the amino acids fraction was higher in vegetative than in reproductive leaves when compared for the same leaf N status. Thus, at high PEPC activity to SPS activity ratio, more 14 C photosynthate was distributed to the amino acid pool, whereas at higher SPS activity, more 14 C was channeled into the carbohydrate fraction. Thus, leaf ontogeny was an important factor controlling photosynthate distribution to the Nor C-pool, respectively, regardless of leaf N status.

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Section: Discussionmentioning

confidence: 85%

Developmental regulation of photosynthate distribution in leaves of rice

Shinano

Nakajima²,

Wasaki

et al. 2006

Photosynt.

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“…There are two possible explanations. First, if phosphofructokinase (PFK(ATP)) catalyses the glycolytic flux, the reduction in the ATP/ADP ratio (Table 2) may offset the increase in the hexose-monophosphate pool, and result in a decrease in the flux through this enzyme (Copeland and Turner 1987).…”

Section: Discussionmentioning

confidence: 99%

The effect of glucose on the control of carbohydrate metabolism in ripening bananas

Hill

Rees

1995

Planta

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Abstract. The effect of exogenous glucose on the major fluxes of carbohydrate metabolism in cores of climacteric fruit of banana (Musa cavendishii Lamb ex Paxton) was determined with the intention of using the effects in the application of top-down metabolic control analysis. Hands of bananas, untreated with ethylene, were allowed to ripen in the dark at 21 ~ Cores were removed from climacteric fruit and incubated in 100 or 200 mM glucose for 4 or 6 h. The rates of starch breakdown, sucrose and fructose accumulation and CO2 production were measured. The steady-state contents of hexose monophosphates, adenylates and pyruvate were determined. In addition, the detailed distribution of label was determined after supply of the following: [U-14C3-, [1-14C]-, [3,4-14C]-and [6-14C]glucose, and [U-lgC]glycerol. The data were used to estimate the major fluxes of carbohydrate metabolism. Supply of exogenous glucose led to increases in the size of the hexose-monophosphate pools. There was a small stimulation of the rate of sugar synthesis and a major increase in the rate of starch synthesis. Starch breakdown was inhibited. Respiration responded to the demand for ATP by sugar synthesis. The effect of glucose on fluxes and metabolite pools is discussed in relation to our understanding of the control and regulation of carbohydrate metabolism in ripening fruit.

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“…the synthesis of fatty acids, of mevalonate and amino acids. In addition, the pentosephosphate pathway generates pentoses and erythrose-4-phosphate for the synthesis of nucleotides and aromatic amino acids (for review see Copeland and Turner, 1987; Turner and Turner, 1980).…”

Section: Introductionmentioning

confidence: 99%

Purification, characterization, and cDNA sequence of glucose‐6‐phosphate dehydrogenase from potato (Solatium tuberosum L.)

1994

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Summary Glucose‐6‐phosphate dehydrogenase (G6PDH, E.C. 1.1.1.49) has been purified from potato tuber at least 850‐fold to apparent homogeneity as judged by SDS‐PAGE. The enzyme was characterized by Km values of 260 μM for glucose‐6‐phosphate and 6 μM for NADP and a broad pH optimum between phi 7.5 and 9. NADPH, GTP, ATP, acetyl CoA and CoA inhibited G6PDH activity. Dithiothreitol (DTT) did not inactivate the enzyme. A highly specific antiserum was produced in a rabbit and used for immunodetection of G6PDH in Western blots. A cDNA library from potato leaves was screened with DNA probes produced by the polymerase chain reaction (PCR) in the presence of g6pdh‐specific primers. A full‐length cDNA clone was analyzed and the derived amino acid sequence compared with known G6PDH sequences from various sources. The homology of the plant sequence with G6PDH sequences from animals and yeast was found to be rather high (52%), whereas there was significantly lower homology with sequences of bacterial origin (37%). The lack of a plastidic signal sequence as well as the insensitivity of the recombinant enzyme towards reduced DTT, support the view that the cDNA sequence of a redox‐independent cytosolic isoform was obtained.

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The Regulation of Glycolysis and the Pentose Phosphate Pathway

Cited by 93 publications

References 127 publications

Developmental regulation of photosynthate distribution in leaves of rice

Developmental regulation of photosynthate distribution in leaves of rice

The effect of glucose on the control of carbohydrate metabolism in ripening bananas

Purification, characterization, and cDNA sequence of glucose‐6‐phosphate dehydrogenase from potato (Solatium tuberosum L.)

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