Direct glucose stimulation of glycogen synthase phosphatase activity in a liver glycogen particle preparation

Daniel P. Gilboe, frank q Nuttall

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

In glycogen particle suspensions prepared from fed rats given either glucagon or glucose in order to increase or decrease the phosphorylase a concentration, respectively, glucose stimulation of synthase phosphatase activity was observed. In preparations from glucagon-treated rats, addition of glucose stimulated synthase and phosphorylase phosphatase simultaneously and not sequentially. Synthase phosphatase stimulation was glucose concentration dependent even when phosphorylase a had been rapidly reduced to a low level. The estimated A0.5 for glucose stimulation of synthase phosphatase activity was 27 mm. An A0.5 for glucose stimulation of phosphorylase phosphatase activity could not be estimated since activity was still increasing with concentrations of glucose as high as 200 mm. In preparations from glucose-treated rats which contain virtually no phosphorylase a, glucose stimulation was still apparent but the A0.5 was increased modestly (36 mm). Stimulation of synthase phosphatase activity was specific for glucose. Several other monosaccharides and the polyhydric alcohol sorbitol were ineffective.

Original languageEnglish (US)
Pages (from-to)587-591
Number of pages5
JournalArchives of Biochemistry and Biophysics
Volume228
Issue number2
DOIs
StatePublished - Feb 1 1984

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