The Regulation of Glycolysis and the Pentose Phosphate Pathway

Turner, John F.; Turner, Donella H.

doi:10.1016/b978-0-12-675402-5.50013-1

Cited by 68 publications

(94 citation statements)

References 150 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These results are consistent with those published for other tissues and indicate that the PFK, PK, and FBPase reactions are tightly regulated in vivo (Leegood and ap Rees, 1978;Turner and Turner, 1980;Day and Lambers, 1983).…”

Section: Regulation Of Carbon Flowsupporting

confidence: 82%

“…The metabolite ratios of the PK-catalyzed reaction in sugarcane are consistent with those published for other tissues (Leegood and ap Rees, 1978;Turner and Turner, 1980;Day and Lambers, 1983). Stimulation of carbon flux into the TCA cycle through activation of PK is traditionally depicted by a decrease in PEP and an attendant increase in pyruvate levels (Kobr and Beevers, 1971;Turner and Turner, 1980;Beaudry et al, 1989).…”

Section: Regulation Of Carbon Flowsupporting

confidence: 75%

“…Stimulation of carbon flux into the TCA cycle through activation of PK is traditionally depicted by a decrease in PEP and an attendant increase in pyruvate levels (Kobr and Beevers, 1971;Turner and Turner, 1980;Beaudry et al, 1989). In sugarcane, the ratio of pyruvate to PEP remained unchanged, indicating that there is no change in the regulation of PK activity associated with the decrease in respiration.…”

Section: Regulation Of Carbon Flowmentioning

confidence: 98%

See 2 more Smart Citations

Carbon Partitioning during Sucrose Accumulation in Sugarcane Internodal Tissue

1997

View full text Add to dashboard Cite

l h e temporal relationship between sucrose (Suc) accumulation and carbon partitioning was investigated in developing sugarcane internodes. Radiolabeling studies on tissue slices, which contained Suc concentrations ranging from 14 to 42% of the dry mass, indicated that maturation coincided with a redirection of carbon from water-insoluble matter, respiration, amino acids, organic acids, and phosphorylated intermediates into SUC. It is evident that a cycle of Suc synthesis and degradation exists in all of the internodes. l h e decreased allocation of carbon to respiration coincides with a decreased flux from the hexose pool. 60th the glucose and fructose (Fru) concentrations significantly decrease during maturation. The phosphoenolpyruvate, Fru-6-phosphate (Fru-6-P), and Fru-2,6-bisphosphate (Fru-2, 6-P,) concentrations decrease between the young and older internodal tissue, whereas the inorganic phosphate concentration increases. lhe calculated mass-action ratios indicate that the ATP-dependent phosphofructokinase, pyruvate kinase, and Fru-l,6-bisphosphatase reactions are tightly regulated in all of the internodes, and no evidence was found that major changes in the regulation of any of these enzymes occur. l h e pyrophosphatedependent phosphofructokinase reaction is in apparent equilibrium in ali the internodes. Substrate availability might be one of the prime factors contributing to the observed decrease in respiration.

show abstract

Section: Regulation Of Carbon Flowsupporting

confidence: 82%

Section: Regulation Of Carbon Flowsupporting

confidence: 75%

Section: Regulation Of Carbon Flowmentioning

confidence: 98%

See 1 more Smart Citation

Carbon Partitioning during Sucrose Accumulation in Sugarcane Internodal Tissue

1997

View full text Add to dashboard Cite

show abstract

“…The Frul ,6Pase will be powerfully inhibited by AMP (27), but PFP will be modulated by PPi. It can be envisaged how rising levels of Fru 1,6P1, and falling Pi signal that surplus carbon is available which cannot be used for respiration or growth (31). Depending on the conditions, either the cytosolic fructose-1,6-bisphosphatase or PFP could catalyse their conversion to hexose P. There are also differences between PFP, and the enzymes which provide the classical control sites for glycolysis.…”

Section: Physiological Consequencesmentioning

confidence: 99%

Product Inhibition of Potato Tuber Pyrophosphate:Fructose-6-Phosphate Phosphotransferase by Phosphate and Pyrophosphate

Stitt

1989

Plant Physiol.

View full text Add to dashboard Cite

The product inhibition of potato (Solanum tuberosum) tuber pyrophosphate:fructose-6-phosphate phosphotransferase by inorganic pyrophosphate and inorganic phosphate has been studied. The binding of substrates for the forward (glycolytic) and the reverse (gluconeogenic) reaction is random order, and occurs with only weak competition between the substrate pair fructose-6-phosphate and pyrophosphate, and between the substrate pair fructose-1,6-bisphosphate and phosphate. Pyrophosphate is a powerful inhibitor of the reverse reaction, acting competitively to fructose-1,6-biphosphate and noncompetitively to phosphate. At the concentrations needed for catalysis of the reverse reaction, phosphate inhibits the forward reaction in a largely noncompetitive mode with respect to both fructose-6-phosphate and pyrophosphate. At higher concentrations, phosphate inhibits both the forward and the reverse reaction by decreasing the affinity for fructose-2,6-bisphosphate and thus, for the other three substrates. These results allow a model to be proposed, which describes the interactions between the substrates at the catalytic site. They also suggest the enzyme may be regulated in vivo by changes of the relation between metabolites and phosphate and could act as a means of controlling the cytosolic pyrophosphate concentration.Control of phosphofructokinase and fructose-1 ,6-bisphosphatase by Fru2,6P2,2 adenylates, and respiratory intermediates provides a framework to understand how glycolysis and gluconeogenesis are controlled in animals and fungi. However, plants possess an enzyme, called PFP, which is capable of substituting for both of these enzymes (1,6,21 (1,8,27).Fru2,6P2 activates PFP but does not activate phosphofructokinase from higher plants (7,21,32 13,14,32). It is also known that Fru6P increases the affinity for Fru2,6P2, while Pi acts in the opposite manner as do a range of other anions (13, 14, 32). These properties have been interpreted as evidence that the physiological role of PFP is in glycolysis (32), or as consistent with it operating in either direction (4), or as not providing any clear evidence about its role (13,14).The following article reapproaches this problem by investigating the interactions between the various potential substrates and products of PFP. The products of a reaction are formed at the catalytic site, and are substrates for the reverse reaction. Consequently a product may act as an inhibitor by occupying the same site on the enzyme as the substrate from which it is derived. Since PFP catalyses a freely reversible reaction which lies close to equilibration in vivo, study of these interactions could be crucial for understanding how it functions in physiological conditions. MATERIALS AND METHODSPFP was partially purified (160-fold) from potato (Solanum tuberosum) tubers (32) and was stored in 50% (v/v) glycerol at 20°C. The preparation was free of ATP phosphofructokinase, aldolase, fructose-1,6-bisphosphatase, and aldolase.Phosphoglucose isomerase was less than 10% of the PFP activity.As...

show abstract

“…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

View full text Add to dashboard Cite

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.

show abstract

The Regulation of Glycolysis and the Pentose Phosphate Pathway

Cited by 68 publications

References 150 publications

Carbon Partitioning during Sucrose Accumulation in Sugarcane Internodal Tissue

Carbon Partitioning during Sucrose Accumulation in Sugarcane Internodal Tissue

Product Inhibition of Potato Tuber Pyrophosphate:Fructose-6-Phosphate Phosphotransferase by Phosphate and Pyrophosphate

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

Contact Info

Product

Resources

About