Requirement of the self-glucosylating initiator proteins Glg1p and Glg2p for glycogen accumulation in Saccharomyces cerevisiae

Christine Cheng, James Mu, Ilona Farkas, Dongqing Huang, Mark G. Goebl, Peter J. Roach

Research output: Contribution to journalArticle

76 Scopus citations

Abstract

Glycogen, a branched polymer of glucose, is a storage molecule whose accumulation is under rigorous nutritional control in many cells. We report the identification of two Saccharomyces cerevisiae genes, GLG1 and GLG2, whose products are implicated in the biogenesis of glycogen. These genes encode self-glucosylating proteins that in vitro can act as primers for the elongation reaction catalyzed by glycogen synthase. Over a region of 258 residues, the Gig proteins have 55% sequence identity to each other and ~33% identity to glycogenin, a mammalian protein postulated to have a role in the initiation of glycogen biosynthesis. Yeast cells defective in either GLG1 or GLG2 are similar to the wild type in their ability to accumulate glycogen. Disruption of both genes results in the inability of the cells to synthesize glycogen despite normal levels of glycogen synthase. These results suggest that a self-glucosylating protein is required for glycogen biosynthesis in a eukaryotic cell. The activation state of glycogen synthase in glg1 glg2 cells is suppressed, suggesting that the Gig proteins may additionally influence the phosphorylation state of glycogen synthase.

Original languageEnglish (US)
Pages (from-to)6632-6640
Number of pages9
JournalMolecular and cellular biology
Volume15
Issue number12
DOIs
StatePublished - Dec 1995

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ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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