Glycogen synthase turnover and phosphorylation in rat H4IIE hepatoma cells

Deborah J. Armstrong, Peter J. Roach

Research output: Contribution to journalArticlepeer-review

Abstract

Glycogen synthase was isolated from rat H4IIE hepatoma cells by the use of specific antibodies. Immunoprecipitates from cells grown in the presence of [35S]methionine contained two 35S-labeled polypeptides, designated GS1 and GS2, separable by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Labeling of both species was half-maximal after 3 h and remained constant up to 48 h. When cells were incubated with [32P]-phosphate, 32P was incorporated into both species with similar kinetics, half-maximal labeling occurring after 2-3 h. The steady-state ratio 32P 35S was significantly higher for the lower mobility GS2 polypeptide. Pulse-chase experiments showed that the two subunits followed similar kinetics with respect to 35S-labeling. However, the turnover of 32P on the GS2 subunit was significantly faster (t 1 2 ~ 30 min) than that on the GS1 subunit (t 1 2 ~ 2 h). We suggest that the two polypeptides represent different phosphorylation states of the glycogen synthase subunit and are rapidly interconverted.

Original languageEnglish (US)
Pages (from-to)16-22
Number of pages7
JournalArchives of Biochemistry and Biophysics
Volume275
Issue number1
DOIs
StatePublished - Nov 15 1989

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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