High concentrations of red blood cell glycogen were visualized by el.ctron microscopy and demonstrated biochemically in amylo1 ,6-glucosidaseand phosphorylase-deficient red blood cells. Glycogen concentration decreased as a function of cell age. Similar incorporation rates of ‘4C-U-glucose into glycogen were observed in amylo-1 ,6-glucosidase-deflcient and normal erythrocytes, characterized by ...

This study investigated the transformational and posttransformational control of skeletal muscle glycogen phosphorylase and pyruvate dehydrogenase (PDH) at three exercise power outputs [35, 65, and 90% of maximal oxygen uptake (VO2 max)]. Seven untrained subjects cycled at one power output for 10 min on three separate occasions, with muscle biopsies at rest and 1 and 10 min of exercise. Glycoge...

Glycogen synthetase was extensively purified from swine kidney by a procedure involving adsorption to calcium phosphate gel, ammonium sulfate fractionation, precipitation with ethanol, and chromatography on DEAE-cellulose. The enzyme was purified more than lO,OOO-fold to a final specific activity of 9.1 pmoles of glucose transferred from UDP-Dglucose to glycogen per min per mg of protein at 37’...

Freezing survival may differ among winters in chorus frogs (Pseudacris triseriata (Wied-Neuwied, 1838)), and low freezing survival is associated with low hepatic glycogen stores. The pattern of prehibernation liver glycogen accumulation in chorus frogs is unknown. Frogs might accumulate hepatic glycogen stores until a threshold level sufficient for winter survival is attained, after which frogs...

Glycogen synthetase was extensively purified from swine kidney by a procedure involving adsorption to calcium phosphate gel, ammonium sulfate fractionation, precipitation with ethanol, and chromatography on DEAE-cellulose. The enzyme was purified more than lO,OOO-fold to a final specific activity of 9.1 pmoles of glucose transferred from UDP-Dglucose to glycogen per min per mg of protein at 37’...

The isolation and crystallization of both forms of glycogen phosphorylase from human skeletal muscle (1) have made possible a detailed study of the properties of these enzymes in comparison with those of rabbit skeletal muscle (2, 3). Phosphorylase b and a from both species have been shown to crystallize under similar conditions and to have similar pH optima, electrophoretic mobilities, sedimen...

A protein kinase, which was produced from its proenzyme occurring in rat brain upon limited proteolysis by a Ca2+-dependent protease from the same tissue (Inoue, M., Kishimoto, A., Takai, Y., and Nishizlka, Y. (1977) J. Biol. Chem. 252, 7610-7616, was capable of phosphorylating alpha and beta subunits of rabbit skeletal muscle glycogen phosphorylase kinase, resulting in a marked enhancement of ...

Phosphorylase is regulated by a number of small-molecular-weight effectors that bind to three sites on the enzyme. Recently, a fourth site referred to as the indole-inhibitor site has been identified. Synthetic compounds bind to the site and inhibit activity. However, the effects of these compounds in the presence of other endogenous effectors are unknown. We have determined the effects of four...

Lack of muscle glycogen phosphorylase activity leads to McArdle's disease, a rare metabolic myopathy. To investigate its molecular basis at the nucleic acid level, we isolated muscle phosphorylase cDNA clones from a human cDNA library in Escherichia coli plasmid pBR 322. Subcloning of one insertion of M13 bacteriophage permitted its definite identification by sequencing. Northern blot experimen...

Mice with muscle-specific knockout of the Glut4 glucose transporter (muscle-G4KO) are insulin resistant and mildly diabetic. Here we show that despite markedly reduced glucose transport in muscle, muscle glycogen content in the fasted state is increased. We sought to determine the mechanism(s). Basal glycogen synthase activity is increased by 34% and glycogen phosphorylase activity is decreased...