Manganese sulfate-dependent glycosylation of endogenous glycoproteins in human skeletal muscle is catalyzed by a nonglucose 6-P-dependent glycogen synthase and not glycogenin

Jin, Ying; Shashkina, Elena; Shashkin, Pavel; Hansson, Anders; Katz, Abram

doi:10.1016/s0304-4165(98)00142-1

Cited by 25 publications

(34 citation statements)

References 41 publications

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“…Under resting conditions, GN-1 is bound to CHO (16,22,30). Two studies have reported observing apo-GN-1 when glycogen concentration was reduced (13,30), although the observations in the former study were made in only two subjects and the latter study used pharmacological levels of epinephrine in an animal model to reduce glycogen. In contrast, we were previously unable to detect apo-GN-1 following prolonged exercise in humans (28).…”

Section: Discussionmentioning

confidence: 99%

Glycogenin protein and mRNA expression in response to changing glycogen concentration in exercise and recovery

Wilson¹,

Gusba²,

Robinson³

et al. 2007

American Journal of Physiology-Endocrinology and Metabolism

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Wilson RJ, Gusba JE, Robinson DL, Graham TE. Glycogenin protein and mRNA expression in response to changing glycogen concentration in exercise and recovery. Am J Physiol Endocrinol Metab 292: E1815-E1822, 2007. First published February 20, 2007 doi:10.1152/ajpendo.00598.2006 is essential for the formation of a glycogen granule; however, rarely has it been studied when glycogen concentration changes in exercise and recovery. It is unclear whether GN-1 is degraded or is liberated and exists as apoprotein (apo)-GN-1 (unglycosylated). To examine this, we measured GN-1 protein and mRNA level at rest, at exhaustion (EXH), and during 5 h of recovery in which the rate of glycogen restoration was influenced by carbohydrate (CHO) provision. Ten males cycled (65% V O2 max) to volitional EXH (117.8 Ϯ 4.2 min) on two separate occasions. Subjects were administered carbohydrate (CHO; 1 g⅐ kg Ϫ1 ⅐ h Ϫ1 Gatorlode) or water [placebo (PL)] during 5 h of recovery. Muscle biopsies were taken at rest, at EXH, and following 30, 60, 120, and 300 min of recovery. At EXH, total glycogen concentration was reduced (P Ͻ 0.05). However, GN-1 protein and mRNA content did not change. By 5 h of recovery, glycogen was resynthesized to ϳ60% of rest in the CHO trial and remained unchanged in the PL trial. GN-1 protein and mRNA level did not increase during recovery in either trial. We observed modest amounts of apo-GN-1 at EXH, suggesting complete degradation of some granules. These data suggest that GN-1 is conserved, possibly as very small, or nascent, granules when glycogen concentration is low. This would provide the ability to rapidly restore glycogen during early recovery. skeletal muscle; carbohydrate; exhaustion; resynthesis; recovery THE SKELETAL MUSCLE ISOFORM of the autoglycosylating protein glycogenin-1 (GN-1) binds a chain of 5-13 glucose molecules (3, 23) at a specific tyrosine residue (Y194) (7,26,29). This is a critical, fundamental step in the formation of a glycogen granule. The covalently associated protein-carbohydrate "primer" serves as a substrate for the catalyzed formation of glycogen by glycogen synthase in concert with branching enzyme (16,25,30).Although it is appreciated that GN-1 is essential for the formation of a glycogen granule, its regulation has rarely been studied in human tissue, and its fate is unknown in circumstances where glycogen stores decrease. Work with cultured myotubes (10) suggests that some glycogen granules may be completely catabolized when glycogen stores are decreased. Under these circumstances, it is unknown whether the protein is degraded or is liberated as apoprotein (apo)-GN-1 (i.e., unglucosylated) and/or is translocated. Presumably, GN-1 would have to be available rapidly when glycogen stores are restored. Examinations of GN-1 in human muscle have focused predominantly on "activity" and mRNA during exercise and recovery. There are reports that GN-1 mRNA increases approximately twofold during prolonged exercise and/or the early part of recovery (14,27,28). Surprisingly, the effects of a ca...

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Section: Discussionmentioning

confidence: 99%

Glycogenin protein and mRNA expression in response to changing glycogen concentration in exercise and recovery

Wilson¹,

Gusba²,

Robinson³

et al. 2007

American Journal of Physiology-Endocrinology and Metabolism

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“…497–501 Moreover, manganese-containing enzymes are involved in diverse metabolic pathways including DNA synthesis 502 and protein modification by glycosylation. 503–505 The effort of redesigning manganese centers into proteins has focused on incorporating a manganese center into a foreign protein scaffold to carry out desired functions, improving native catalytic activity, and creating a novel magnanese binding site with functional importance. These studies have addressed different fundamental aspects of structure–function relationships in metalloenzymes and propelled the design of novel functional metalloenzymes toward potential applications in therapeutics.…”

Section: Protein Redesignmentioning

confidence: 99%

Protein Design: Toward Functional Metalloenzymes

et al. 2014

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“…For analysis of glycogen, muscle powder was digested in hot 1 M KOH, hydrolysed enzymatically and analysed for free glucose as described elsewhere [15]. For analyses of enzyme activities muscle powder was homogenized (100 µl/mg dry wt) in ice-cold buffer consisting of 10 mM EDTA, 50 mM potassium fluoride, 30% (v/v) glycerol, pH 7.0.…”

Section: Analysesmentioning

confidence: 99%

“…The homogenate was centrifuged at 23,000 g for 15 min at 4°C. Aliquots of the supernatant were diluted and assayed with filter paper techniques following the incorporation of [ 14 C]glucose from UDP-glucose (for analysis of GS) or glucose-1-P (for analysis of phosphorylase) into glycogen at 30°C as described elsewhere [15]. Briefly, GS activity was measured in the presence of 0.17 or 7.2 mM glucose-6-P. Phosphorylase activity was measured in the absence and presence of 3.3 mM AMP.…”

Section: Analysesmentioning

confidence: 99%

“…However, it is well documented that after an initial increase, phosphorylase fractional activity decreases in contracting muscle, even to values below baseline [7,25]. Furthermore, the low fractional activity at the end of contraction can decrease even further during recovery [15]. Moreover, the ability to activate (phosphorylate) phosphorylase during recovery from repeated contraction is diminished markedly and this phenomenon has been shown to persist for at least 90 min [8].…”

Section: Phosphorylasementioning

confidence: 99%

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Insulin-independent glycogen supercompensation in isolated mouse skeletal muscle: role of phosphorylase inactivation

Sandström

Abbate

Andersson

et al. 2004

Pflugers Arch - Eur J Physiol

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Glycogen supercompensation (increase in muscle glycogen content above basal) is an established phenomenon induced by unknown mechanisms. It consists of both insulin-dependent and -independent components. Here, we investigate insulin-independent glycogen supercompensation in isolated, intact extensor digitorum longus muscles from mice. Muscles were stimulated electrically, incubated in vitro with 5.5 mM glucose for up to 16 h and then analysed for glycogen, glucose uptake and enzyme activities. Basal glycogen was 84+/-6 micro mol glucosyl units/g dry muscle and was depleted by 80% after 10 min contraction. Glycogen increased after contraction, reaching a peak value of 113+/-9 micro mol glucosyl units/g dry muscle ( P<0.05 vs. basal) by 6 h, and returned to basal values by 16 h (84+/-8). Maximal activities of glycogen synthase, phosphorylase and alpha-glucosidase were not significantly altered by contraction or during the 6-h recovery period. Glycogen synthase fractional activity (0.17/7.2 mM glucose-6-P; inversely related to phosphorylation state of the enzyme) was increased about twofold early after contraction but then decreased and was slightly lower than baseline during the period of supercompensation (4-6 h). Phosphorylase fractional activity (+/-adenosine monophosphate; directly related to phosphorylation state of the enzyme) decreased to 60% of basal after contraction and decreased further during the initial 4 h of recovery to 40% of basal ( P<0.01 vs. basal). After 4 h recovery, glucose uptake was slightly (50%) higher in the stimulated than in the non-stimulated muscle ( P<0.01). Thus, insulin-independent glycogen supercompensation involves inactivation of phosphorylase and hence an inhibition of glycogen breakdown.

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Manganese sulfate-dependent glycosylation of endogenous glycoproteins in human skeletal muscle is catalyzed by a nonglucose 6-P-dependent glycogen synthase and not glycogenin

Cited by 25 publications

References 41 publications

Glycogenin protein and mRNA expression in response to changing glycogen concentration in exercise and recovery

Glycogenin protein and mRNA expression in response to changing glycogen concentration in exercise and recovery

Protein Design: Toward Functional Metalloenzymes

Insulin-independent glycogen supercompensation in isolated mouse skeletal muscle: role of phosphorylase inactivation

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