Labeling of rat liver glucose-1-phosphate, glucose-6-phosphate, uridine diphosphate glucose, and glycogen during glycogen synthesis

Das, Indrajit; Sie, Hsien-Gieh; Fishman, William H.

doi:10.1016/0003-9861(71)90378-x

Cited by 14 publications

(11 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…G6P is not only an intermediate of glucose utilization and production but also a regulator of gene expression and enzyme activity (1). This hypothesis would be consistent with studies that provided indirect evidence for multiple G6P pools (8,32).…”

Section: Discussionsupporting

confidence: 81%

Evidence for High-Capacity Bidirectional Glucose Transport across the Endoplasmic Reticulum Membrane by Genetically Encoded Fluorescence Resonance Energy Transfer Nanosensors

Fehr

Takanaga

Ehrhardt

et al. 2005

Molecular and Cellular Biology

104

View full text Add to dashboard Cite

Glucose release from hepatocytes is important for maintenance of blood glucose levels. Glucose-6-phosphate phosphatase, catalyzing the final metabolic step of gluconeogenesis, faces the endoplasmic reticulum (ER) lumen. Thus, glucose produced in the ER has to be either exported from the ER into the cytosol before release into circulation or exported directly by a vesicular pathway. To measure ER transport of glucose, fluorescence resonance energy transfer-based nanosensors were targeted to the cytosol or the ER lumen of HepG2 cells. During perfusion with 5 mM glucose, cytosolic levels were maintained at ϳ80% of the external supply, indicating that plasma membrane transport exceeded the rate of glucose phosphorylation. Glucose levels and kinetics inside the ER were indistinguishable from cytosolic levels, suggesting rapid bidirectional glucose transport across the ER membrane. A dynamic model incorporating rapid bidirectional ER transport yields a very good fit with the observed kinetics. Plasma membrane and ER membrane glucose transport differed regarding sensitivity to cytochalasin B and showed different relative kinetics for galactose uptake and release, suggesting catalysis by distinct activities at the two membranes. The presence of a high-capacity glucose transport system on the ER membrane is consistent with the hypothesis that glucose export from hepatocytes occurs via the cytosol by a yet-to-be-identified set of proteins.

show abstract

Section: Discussionsupporting

confidence: 81%

Evidence for High-Capacity Bidirectional Glucose Transport across the Endoplasmic Reticulum Membrane by Genetically Encoded Fluorescence Resonance Energy Transfer Nanosensors

Fehr

Takanaga

Ehrhardt

et al. 2005

Molecular and Cellular Biology

104

View full text Add to dashboard Cite

show abstract

“…in pigeon liver homogenate. This is in agreement with our earlier in viva demonstration of glucose-l-P as the earliest detectable product of glucose phosphoryIation [8] and lends support to a number of other recent communications suggesting a new route of glucose metabolism in certain tissues (see Antony et al [2]). …”

Section: * Present Address: Department Of Biochemistry Imperialsupporting

confidence: 92%

“…The purified glucose-6-P and glucose-1-P were hydrolysed in acid and the free glucose extracted from the paper after chromatography in the aqueous phenolic solvent of Putman [lo] . Specific radioactivity was determined by enzymatic assay of its glucose concentrations [8] and by the liquid scintillation counting of the same solution ill]. The amounts of glucose-6-P and glucose-l-P synthesized in 5 min by liver homogenate and their respective specific radioactivities together with that of the precursor giucose are shown on table 1.…”

Section: * Present Address: Department Of Biochemistry Imperialmentioning

confidence: 99%

“…The reaction was stopped by the addition of an equal vol of 1.2 M perchloric acid. Following the enzymatic dete~ination of the amount of glucose, glucose-6-P and glucose-l-P in neutralized perchloric acid supernate of both the experiments and controls [8], a known amount of glucose-6-P and glucose-l-P as carrier was added to the experimental perchloric acid supernate for further purification of the sugar phosphates.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Primary incorporation of U‐¹⁴C‐glucose into glucose‐1‐phosphate and glucose‐6‐phosphate by incubated pigeon liver homogenate

Das

Sie

1972

FEBS Letters

Self Cite

View full text Add to dashboard Cite

That glucose-6-P is a necessary step in the transformation of glucose to glycogen has been questioned in several reports using homogenates and slices from rat liver [l-3] , or pigeon liver homogenate [4] .The work of Pocchiari [S] on the incubated rat diaphram has also led others [6] to suggest that glucosed-P might not be the only immediate product of glucose phosphorylation.Glycogen synthesis from glucose was shown by pigeon liver homogenate [4, '71. This provides an ideal, cell-free system for following the incorporation of "C-glucose into glucose-6-P and glucose-l-P, which is described in the present communication.The preparation of pigeon liver homogenate and of the incubation mixture was as described by Nigam and Fridland [7]. A total of 24 flasks were incubated for 5 min at 37", each flask containing 1 &i of radioactivity and 100 @moles of glucose in 10 ml. The control flasks were incubated similarly without glucose. The reaction was stopped by the addition of an equal vol of 1.2 M perchloric acid. Following the enzymatic dete~ination of the amount of glucose, glucose-6-P and glucose-l-P in neutralized perchloric acid supernate of both the experiments and controls [8], a known amount of glucose-6-P and glucose-l-P as carrier was added to the experimental perchloric acid supernate for further purification of the sugar phosphates.

show abstract

“…A kinetic study of [14C]fructose metabolism in liver after intravenous injection provided evidence for compartmentation of Glc6P and triose phosphates into gluconeogenic and glycolytic pools [7]. A similar experiment with ['4C]glucose gave results compatible with multiple pools of Glc6P, one of which was on the glycogenic pathway [8].…”

Section: Introductionmentioning

confidence: 94%

Compartmentation of glucose 6-phosphate in hepatocytes

Kalant

Parniak

Lemieux

1987

Biochemical Journal

View full text Add to dashboard Cite

Rat hepatocytes were incubated with 14C-labelled hexoses, and the specific radioactivities of glucose 6-phosphate, glucose 1-phosphate and fructose 6-phosphate were determined. (1) When suspensions of freshly isolated hepatocytes were incubated with [14C]glucose, the specific radioactivities of glucose 1-phosphate and fructose 6-phosphate were severalfold higher than that of glucose 6-phosphate. The ratios of the specific radioactivities decreased with time of incubation. These relationships were also found when incubations were carried out with primary cultures of rat hepatocytes or with crude homogenates of hepatocytes, but not with isolated nuclei. (2) When cells were incubated with [14C]fructose, the ratios of the specific radioactivities were higher than with [14C]glucose, and also decreased with time. (3) Paired incubations were carried out with a mixture of galactose and fructose, with one or other sugar being labelled with 14C. The specific radioactivity of glucose released into the medium was greater than that of glucose 6-phosphate when fructose was labelled, but not when galactose was labelled. Furthermore, glucose 6-phosphate and glucose in the medium differed with regard to the distribution of 14C between C-1 and C-6. These results are interpreted as evidence that glucose 6-phosphate in hepatocytes does not exist as a homogeneous pool, but that subcompartments exist which are associated with glucose phosphorylation, gluconeogenesis and glycogenolysis.

show abstract

Labeling of rat liver glucose-1-phosphate, glucose-6-phosphate, uridine diphosphate glucose, and glycogen during glycogen synthesis

Cited by 14 publications

References 17 publications

Evidence for High-Capacity Bidirectional Glucose Transport across the Endoplasmic Reticulum Membrane by Genetically Encoded Fluorescence Resonance Energy Transfer Nanosensors

Evidence for High-Capacity Bidirectional Glucose Transport across the Endoplasmic Reticulum Membrane by Genetically Encoded Fluorescence Resonance Energy Transfer Nanosensors

Primary incorporation of U‐¹⁴C‐glucose into glucose‐1‐phosphate and glucose‐6‐phosphate by incubated pigeon liver homogenate

Compartmentation of glucose 6-phosphate in hepatocytes

Contact Info

Product

Resources

About

Labeling of rat liver glucose-1-phosphate, glucose-6-phosphate, uridine diphosphate glucose, and glycogen during glycogen synthesis

Cited by 14 publications

References 17 publications

Evidence for High-Capacity Bidirectional Glucose Transport across the Endoplasmic Reticulum Membrane by Genetically Encoded Fluorescence Resonance Energy Transfer Nanosensors

Evidence for High-Capacity Bidirectional Glucose Transport across the Endoplasmic Reticulum Membrane by Genetically Encoded Fluorescence Resonance Energy Transfer Nanosensors

Primary incorporation of U‐14C‐glucose into glucose‐1‐phosphate and glucose‐6‐phosphate by incubated pigeon liver homogenate

Compartmentation of glucose 6-phosphate in hepatocytes

Contact Info

Product

Resources

About

Primary incorporation of U‐¹⁴C‐glucose into glucose‐1‐phosphate and glucose‐6‐phosphate by incubated pigeon liver homogenate