Studies on UDPG-Glycogen Transglucosylase. I. Preparation and Differentiation of Two Activities of UDPG-Glycogen Transglucosylase from Rat Skeletal Muscle<sup>*</sup>

Rosell-Pérez, M; Villar-Palasí, Carlos; Larner, Joseph

doi:10.1021/bi00911a005

Cited by 160 publications

(33 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Alternatively, storage ofglucose as glycogen is the predominant route of nonoxidative glucose metabolism under conditions of insulin stimulation (2,3), and its rate appears to be regulated by the enzyme glycogen synthase (3). In muscle, glycogen synthase (GS) is activated by its allosteric effector G6P (4,5) and in human muscle is dephosphorylated and activated by insulin infusion (6-9). Activation of muscle GS by insulin in man has been correlated with the activation of nonoxidative glucose metabolism by insulin in studies in which nonoxidative glucose metabolism was defined as the difference between isotopically determined overall glucose disposal and overall glucose oxidation determined by indirect calorimetry (3).…”

Section: Introductionmentioning

confidence: 99%

Effects of insulin infusion on human skeletal muscle pyruvate dehydrogenase, phosphofructokinase, and glycogen synthase. Evidence for their role in oxidative and nonoxidative glucose metabolism.

Mandarino¹,

Kc²,

Verity³

et al. 1987

J. Clin. Invest.

194

117

View full text Add to dashboard Cite

To determine whether activation by insulin of glycogen synthase (GS), phosphofructokinase (PFK), or pyruvate dehydrogenase (PDH) in skeletal muscle regulates intracellular glucose metabolism, subjects were studied basally and during euglycemic insulin infusions of 12, 30, and 240 MU/im2 nmn. Glucose disposal, oxidative and nonoxidative glucose metabolism were determined. GS, PFK, and PDH were assayed in skeletal muscle under each condition. Glucose disposal rates were 2.37+0.11, 3.15±0.19, 6.71±0.44, and 11.7±1.73 mg/kg. min; glucose oxidation rates were 1.96±0.18, 2.81±0.28, 4.43±0.32, and 5.22+0.52. Nonoxidative glucose metabolism was 0.39±0.13, 0.34±0.26, 2.28±0.40, and 6.52±1.21 mg/kg. min. Both the proportion of active GS and the proportion of active PDH were increased by hyperinsulinemia. PFK activity was unaffected. Activation of GS was correlated with nonoxidative glucose metabolism, while activation of PDH was correlated with glucose oxidation. Sensitivity to insulin of GS was similar to that of nonoxidative glucose metabolism, while the sensitivity to insulin of PDH was similar to that of glucose oxidation. Therefore, the activation of these enzymes in muscle may regulate nonoxidative and oxidative glucose metabolism.

show abstract

Section: Introductionmentioning

confidence: 99%

Effects of insulin infusion on human skeletal muscle pyruvate dehydrogenase, phosphofructokinase, and glycogen synthase. Evidence for their role in oxidative and nonoxidative glucose metabolism.

Mandarino¹,

Kc²,

Verity³

et al. 1987

J. Clin. Invest.

194

117

View full text Add to dashboard Cite

show abstract

“…G-6-P is a potent activator of the phosphorylated (inactive) form of GS (Rosell-Perez et al 1962) and an inhibitor of the dephosphorylated (inactive) form of GP (Morgan & Parmeggiani, 1964). However, the G-6-P content did not differ between groups, and therefore cannot explain the dissociation between glycogen levels and the activities of GP and GS.…”

Section: Discussionmentioning

confidence: 99%

Altered Glycogen Synthase and Phosphorylase Activities in Skeletal Muscle of Tetraplegic Patients

Jin

Shashkin

Hjeltnes

et al. 2001

Experimental Physiology

View full text Add to dashboard Cite

Despite marked differences in both the extent of physical activity and in muscle metabolism and structure between tetraplegic and control subjects, the glycogen content in the skeletal muscle of both groups is similar. We determined whether this similarity could be explained by the activities of key enzymes of glycogen metabolism. Muscle biopsies were analysed for glycogen synthase (GS) and glycogen phosphorylase (GP) activities, as well as for metabolites. Glycogen content did not differ significantly between the two groups. Total glycogen synthase activity was reduced by almost 60% in tetraplegics (P < 0.01), whereas total phosphorylase activity did not differ between groups. GS fractional activity did not differ between groups, whereas phosphorylase fractional activity (−/+ AMP) was significantly higher in the tetraplegics (0.08 ± 0.01, control; 0.25 ± 0.02, tetraplegics; P < 0.001). Neither uridine diphosphate (UDP)‐glucose nor glucose 6‐phosphate (G‐6‐P) content in muscle differed significantly between groups. These data demonstrate that, in tetraplegics, muscle glycogen content is preserved despite decreases in GS activity and increases in phosphorylase fractional activity. Muscle paralysis has differential effects on the activities of GS and GP.

show abstract

“…By contrast, glucose-6-P does not influence the V,,, of synthetase I, but it does cause a decrease in the apparent K , for UDPG (192,194,197,198). * It has been suggested (202) that glycogen might serve as a negative feedback effector in the conversion of the I form to the D form and thereby regulate its own synthesis.…”

Section: Glycogen Synthetasementioning

confidence: 99%

Allosteric Regulation of Enzyme Activity

Er¹

1966

Advances in Enzymology - And Related Areas of Molecular Biology

View full text Add to dashboard Cite

Studies on UDPG-Glycogen Transglucosylase. I. Preparation and Differentiation of Two Activities of UDPG-Glycogen Transglucosylase from Rat Skeletal Muscle^*

Cited by 160 publications

References 13 publications

Effects of insulin infusion on human skeletal muscle pyruvate dehydrogenase, phosphofructokinase, and glycogen synthase. Evidence for their role in oxidative and nonoxidative glucose metabolism.

Effects of insulin infusion on human skeletal muscle pyruvate dehydrogenase, phosphofructokinase, and glycogen synthase. Evidence for their role in oxidative and nonoxidative glucose metabolism.

Altered Glycogen Synthase and Phosphorylase Activities in Skeletal Muscle of Tetraplegic Patients

Allosteric Regulation of Enzyme Activity

Contact Info

Product

Resources

About

Studies on UDPG-Glycogen Transglucosylase. I. Preparation and Differentiation of Two Activities of UDPG-Glycogen Transglucosylase from Rat Skeletal Muscle*

Cited by 160 publications

References 13 publications

Effects of insulin infusion on human skeletal muscle pyruvate dehydrogenase, phosphofructokinase, and glycogen synthase. Evidence for their role in oxidative and nonoxidative glucose metabolism.

Effects of insulin infusion on human skeletal muscle pyruvate dehydrogenase, phosphofructokinase, and glycogen synthase. Evidence for their role in oxidative and nonoxidative glucose metabolism.

Altered Glycogen Synthase and Phosphorylase Activities in Skeletal Muscle of Tetraplegic Patients

Allosteric Regulation of Enzyme Activity

Contact Info

Product

Resources

About

Studies on UDPG-Glycogen Transglucosylase. I. Preparation and Differentiation of Two Activities of UDPG-Glycogen Transglucosylase from Rat Skeletal Muscle^*