Regulation of glycogen synthetase and phosphorylase phosphatase activities in rat adipose tissue

Barash, V.; Schramm, H; Gutman, Alexander B.

doi:10.1016/0005-2744(77)90140-1

Cited by 13 publications

(6 citation statements)

References 15 publications

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“…Glycogen synthase activity was assayed according to Thomas et al (25). One unit of glycogen synthase was defined as the amount of enzyme that catalyzes the incorporation of 1 mol of UDP-glucose into glycogen per min (26). PDH activity was assayed as described previously (18).…”

Section: Methodsmentioning

confidence: 99%

In L6 Skeletal Muscle Cells, Glucose Induces Cytosolic Translocation of Protein Kinase C-α and Trans-activates the Insulin Receptor Kinase

Caruso

Miele

Oriente

et al. 1999

Journal of Biological Chemistry

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In L6 skeletal muscle cells expressing human insulin receptors (L6(hIR)), exposure to 25 mM glucose for 3 min induced a rapid 3-fold increase in GLUT1 and GLUT4 membrane translocation and glucose uptake. The high glucose concentration also activated the insulin receptor kinase toward the endogenous insulin receptor substrates (IRS)-1 and IRS-2. At variance, in L6 cells expressing kinase-deficient insulin receptors, the exposure to 25 mM glucose elicited no effect on glucose disposal. In the L6(hIR) cells, the acute effect of glucose on insulin receptor kinase was paralleled by a 2-fold decrease in both the membrane and the insulin receptor co-precipitated protein kinase C (PKC) activities and a 3-fold decrease in receptor Ser/Thr phosphorylation. Western blotting of the receptor precipitates with isoform-specific PKC antibodies revealed that the glucose-induced decrease in membrane- and receptor-associated PKC activities was accounted for by dissociation of PKCalpha but not of PKCbeta or -delta. This decrease in PKCalpha was paralleled by a similarly sized increase in cytosolic PKCalpha. In intact L6(hIR) cells, inhibition of PKCalpha expression by using a specific antisense oligonucleotide caused a 3-fold increase in IRS phosphorylation by the insulin receptor. This effect was independent of insulin and accompanied by a 2.5-fold increase in glucose disposal by the cells. Thus, in the L6 skeletal muscle cells, glucose acutely regulates its own utilization through the insulin signaling system, independent of insulin. Glucose autoregulation appears to involve PKCalpha dissociation from the insulin receptor and its cytosolic translocation.

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Section: Methodsmentioning

confidence: 99%

In L6 Skeletal Muscle Cells, Glucose Induces Cytosolic Translocation of Protein Kinase C-α and Trans-activates the Insulin Receptor Kinase

Caruso

Miele

Oriente

et al. 1999

Journal of Biological Chemistry

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“…Additional measurements included phosphorylase activity [12), ol-l,6-amyloglucosidase fl31, glycogen content [14}, and protein concentration 1151.…”

Section: Enzyme Activity Measurementsmentioning

confidence: 99%

Hereditary branching enzyme dysfunction in adult polyglucosan body disease: A possible metabolic cause in two patients

Lossos

Barash

Soffer

et al. 1991

Annals of Neurology

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We describe 2 unrelated patients with adult polyglucosan body disease (APBD) diagnosed by sural nerve biopsy. Both patients were offspring of consanguineous marriages. They presented clinically with late onset pyramidal tetraparesis, micturition difficulties, peripheral neuropathy, and mild cognitive impairment. Magnetic resonance imaging of the brain revealed extensive white matter abnormalities in both. In search of a possible metabolic defect, we evaluated glycogen metabolism in these patients and their clinically unaffected children. Branching enzyme activity in the patients' polymorphonuclear leukocytes was about 15% of control values, whereas their children displayed values of 50 to 60%, suggesting a possible autosomal recessive mode of transmission. This is the first report of an inherited metabolic defect in patients with adult polyglucosan body disease. We suggest that branching enzyme dysfunction may be implicated in the pathogenesis of some patients with adult polyglucosan body disease.

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“…The molar ratio of GS^gg^ subunit to cAMP-dependent protein kinase catalytic subunit varied from 5 to 100. The most likely reason for the lack of reactivity of ----ATP concentration appeared to be an ATP effect on glycogen synthase.ATP has been shown by several investigators to be an inhibitor of both glycogen synthase I and D(19)(20)(21)(22)(23)(24). These data suggest that there are at least two binding sites for this nucleotide triphosphate.…”

mentioning

confidence: 86%

“…Both forms of glycogen synthase isolated from liver (18,19), skeletal muscle (. 20,21), heart (21,22), adipose tissue (23) and yeast (24) are subject to allosteric regulation by nucleotides, inorganic phosphate and glucose-6-phosphate.…”

mentioning

confidence: 99%

“…Nucleotide inhibition seems to be due to two distinct types: 1) directly competitive with the physiological substrate UDP-glucose (19,20,(22)(23)(24) and 2) cooperative, as described by Rothman and Cabib (24), Piras e;t ai, (20) and Nakai and Thomas (22), Activation by glucose-6phosphate is also apparently allosteric effecting kinetic constants for the physiological substrate UDP-glucose (18,19,21,24). Inorganic phos phate activates glycogen synthase I (18) but inhibits glycogen synthase D (18,19,22).…”

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confidence: 99%

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The phosphorylation of bovine heart glycogen synthase

Mitchell

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Regulation of glycogen synthetase and phosphorylase phosphatase activities in rat adipose tissue

Cited by 13 publications

References 15 publications

In L6 Skeletal Muscle Cells, Glucose Induces Cytosolic Translocation of Protein Kinase C-α and Trans-activates the Insulin Receptor Kinase

In L6 Skeletal Muscle Cells, Glucose Induces Cytosolic Translocation of Protein Kinase C-α and Trans-activates the Insulin Receptor Kinase

Hereditary branching enzyme dysfunction in adult polyglucosan body disease: A possible metabolic cause in two patients

The phosphorylation of bovine heart glycogen synthase

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