The molecular size and shape of liver glycogen

Geddes, Robert; Harvey, J.D.; Wills, Peter R.

doi:10.1042/bj1630201

Cited by 86 publications

(33 citation statements)

References 27 publications

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“…VOL. 21,2001 Snf1p KINASE, Pho85p KINASE, GLYCOGEN, AND AUTOPHAGY 5745 on May 9, 2018 by guest http://mcb.asm.org/ ment of glycogen in apg13 cells gave similar results (data not shown). Therefore, the defect in the apg1 mutant was not its ability to synthesize glycogen, but rather its ability to maintain the stores late into the stationary phase.…”

Section: Resultssupporting

confidence: 75%

“…This behavior is qualitatively VOL. 21,2001 Snf1p KINASE, Pho85p KINASE, GLYCOGEN, AND AUTOPHAGY 5747 the same as the EG328-1A strain, except that the time frame is slower, and more time is needed for complete loss of glycogen in the apg7 mutants with the TN125 background. The alkaline phosphatase activity was increased three-to fourfold as the cells exited from the exponential phase and remained elevated throughout the stationary phase, suggesting that autophagy is induced under these conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Our study shows that autophagic activity is induced during the transition from loga- VOL. 21,2001 Snf1p KINASE, Pho85p KINASE, GLYCOGEN, AND AUTOPHAGY 5749 rithmic to stationary phase, consistent with the cells adapting to an altered nutritional environment. SNF1 has long been known for its roles in glucose repression and glycogen accumulation, and so linking it to another response associated with nutritional controls is perhaps not surprising.…”

Section: Discussionmentioning

confidence: 98%

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Antagonistic Controls of Autophagy and Glycogen Accumulation by Snf1p, the Yeast Homolog of AMP-Activated Protein Kinase, and the Cyclin-Dependent Kinase Pho85p

Wang

Wilson

Fujino

et al. 2001

Molecular and Cellular Biology

273

242

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In the yeast Saccharomyces cerevisiae, glycogen is accumulated as a carbohydrate reserve when cells are deprived of nutrients. Yeast mutated in SNF1, a gene encoding a protein kinase required for glucose derepression, has diminished glycogen accumulation and concomitant inactivation of glycogen synthase. Restoration of synthesis in an snf1 strain results only in transient glycogen accumulation, implying the existence of other SNF1-dependent controls of glycogen storage. A genetic screen revealed that two genes involved in autophagy, APG1 and APG13, may be regulated by SNF1. Increased autophagic activity was observed in wild-type cells entering the stationary phase, but this induction was impaired in an snf1 strain. Mutants defective for autophagy were able to synthesize glycogen upon approaching the stationary phase, but were unable to maintain their glycogen stores, because subsequent synthesis was impaired and degradation by phosphorylase, Gph1p, was enhanced. Thus, deletion of GPH1 partially reversed the loss of glycogen accumulation in autophagy mutants. Loss of the vacuolar glucosidase, SGA1, also protected glycogen stores, but only very late in the stationary phase. Gph1p and Sga1p may therefore degrade physically distinct pools of glycogen. Pho85p is a cyclin-dependent protein kinase that antagonizes SNF1 control of glycogen synthesis. Induction of autophagy in pho85 mutants entering the stationary phase was exaggerated compared to the level in wild-type cells, but was blocked in apg1 pho85 mutants. We propose that Snf1p and Pho85p are, respectively, positive and negative regulators of autophagy, probably via Apg1 and/or Apg13. Defective glycogen storage in snf1 cells can be attributed to both defective synthesis upon entry into stationary phase and impaired maintenance of glycogen levels caused by the lack of autophagy.Cells constantly abstract information about their environment and modify their cellular and metabolic programs to cope with the prevailing conditions. For unicellular organisms like the budding yeast, Saccharomyces cerevisiae, much of the information about nutritional status is carried by the nutrients themselves. Depending on the type and availability of carbon, nitrogen, sulfur, and other requirements, the appropriate metabolic and cellular programs are elicited. Exhaustion of a preferred carbon source, like glucose, signals the induction of numerous genes needed to change to other metabolic regimes, in part by derepression of glucose-repressed genes and in part by cyclic AMP (cAMP) pathway control of gene expression (18,30). Another decision linked to nutritional deprivation is the synthesis of storage compounds like glycogen and trehalose, which are the primary carbohydrate reserves of the yeast (15). Glycogen is a branched polymer of glucose units that acts as a reserve of glucose and energy (47). In yeast growing on glucose, glycogen is synthesized late in the logarithmic phase and begins to be utilized when cells enter the stationary phase (7,8,37). However, glycogen stores can be p...

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 98%

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Antagonistic Controls of Autophagy and Glycogen Accumulation by Snf1p, the Yeast Homolog of AMP-Activated Protein Kinase, and the Cyclin-Dependent Kinase Pho85p

Wang

Wilson

Fujino

et al. 2001

Molecular and Cellular Biology

273

242

View full text Add to dashboard Cite

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“…These short‐term fluctuations in body weight are assumed to be due to variations in several factors such as intestinal contents (Institute of Medicine of the National Academies, 2005; EFSA Panel on Dietetic Products, Nutrition, and Allergies [NDA], 2010), glycogen stores (Geddes et al. 1977; Fernandez‐Elias et al. 2015), labile protein stores (Swick and Benevenga 1977), and the accompanying body water (Oian et al.…”

Section: Introductionmentioning

confidence: 99%

Composition of two-week change in body weight under unrestricted free-living conditions

et al. 2017

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The composition of weight change has a large impact on energy balance calculations. Composition of long‐term weight change interventions is well‐documented, but information on short‐term weight change under unrestricted free‐living conditions is limited. The composition and energy density of the changes in body weight during 2‐week free‐living conditions were analyzed in adults from two cohorts: cohort 1 (n = 24) included participants from the reproducibility subset of the Observing Protein and Energy Nutrition study; cohort 2 (n = 22) included participants who were studied under free‐living conditions in an ongoing study in the Chicago area. Change in body weight, total body water (TBW) by stable isotope dilution (cohort 1), and fat mass (FM) and fat‐free mass (FFM) by serial DXA (cohort 2) were measured. To determine the fractional composition of the change in body weight we analyzed the linear associations between changes in body weight and changes in body composition. In the combined dataset, the average change in body weight (0.26 ± 1.2 kg) was consistent with being in energy balance. Average change in body weight was associated with the change in TBW (P < 0.0001) in cohort 1 and the change in FFM (P = 0.0002) in cohort 2. A unit change in body weight was composed of 84% change in FFM in the combined dataset indicating that 2‐week fluctuation in body weight is largely composed of FFM. The energy density of 1–3 kg short‐term changes in body weight averaged 2380 kcal/kg.

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“…The advantages of such hyperbranched polyglucan biohybrids are multiple and cover a range of potential applications. For example, glycogen, the energy storage polymer of mammals, is a hyperbranched glycoconjugate itself as it is in vivo grown from a central core protein known as glycogenin [39][40][41]. The in vitro approach as described in this paper to design synthetic hyperbranched glycoconjugates, may be a valuable tool in order to completely understand the biosynthesis of glycogen and its aggregation behavior.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Hyperbranched Glycoconjugates by the Combined Action of Potato Phosphorylase and Glycogen Branching Enzyme from Deinococcus geothermalis

et al. 2012

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Abstract:Potato phosphorylase is able to synthesize linear polyglucans from maltoheptaose primers. By coupling maltoheptaose to butane diamine, tris(2-aminoethyl)amine and amine functionalized amine functionalized poly ethyleneglycol (PEG), new primer molecules became available. The resulting di-, tri-and macro-primers were incubated with potato phosphorylase and glycogen branching enzyme from Deinococcus geothermalis. Due to the action of both enzymes, hyperbranched polyglucan arms were grown from the maltoheptaose derivatives with a maximum degree of branching of 11%. The size of the synthesized hyperbranched polyglucans could be controlled by the ratio monomer over primer. About 60%-80% of the monomers were incorporated in the glycoconjugates. The resulting hyperbranched glycoconjugates were subjected to Dynamic Light Scattering (DLS) measurements in order to determine the hydrodynamic radius and it became obvious that the structures formed agglomerates in the range of 14-32 nm.

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The molecular size and shape of liver glycogen

Cited by 86 publications

References 27 publications

Antagonistic Controls of Autophagy and Glycogen Accumulation by Snf1p, the Yeast Homolog of AMP-Activated Protein Kinase, and the Cyclin-Dependent Kinase Pho85p

Antagonistic Controls of Autophagy and Glycogen Accumulation by Snf1p, the Yeast Homolog of AMP-Activated Protein Kinase, and the Cyclin-Dependent Kinase Pho85p

Composition of two-week change in body weight under unrestricted free-living conditions

Synthesis of Hyperbranched Glycoconjugates by the Combined Action of Potato Phosphorylase and Glycogen Branching Enzyme from Deinococcus geothermalis

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