High impact information on Gyg1

• 2) When these astrocytes are fed with glucose, proglycogen is synthesized from the glycogenin primer by a glycogen-synthase-like UDPglucose transglucosylase activity (proglycogen synthase) distinct from the well-recognized glycogen synthase, and synthesis stops at this point [1].
• Glycogen synthesis in the astrocyte: from glycogenin to proglycogen to glycogen [1].
• A xylosyltransferase in rat kidney, tentatively identified as glycogenin (Meezan, E., Ananth, S., Manzella, S., Campbell, P., Siegal, S., Pillion, D. J., and Rodén, L. (1994) J. Biol. Chem. 269, 11503-11508), was purified by a procedure in which affinity chromatography on UDP-glucuronic acid-agarose was a particularly useful step [2].
• In contrast to glycogenin, glycogen synthase did not catalyze transfer from UDP-xylose, and it is suggested that the incorporation of xylose into glycogen observed by other investigators was due to glycogenin-catalyzed xylosyl transfer and subsequent chain elongation by glycogen synthase [2].
• In this study we found no evidence for hormonal control of the glucosylation state of glycogenin in hepatocytes [3].

Biological context of Gyg1

• A 1624 bp fragment of rat glycogenin was cloned by RT-PCR that includes a 1002 bp open reading frame encoding a 333 amino acid protein [4].
• Utilizing the differential display technique to analyze changes in gene expression during early postnatal cardiac development, we have isolated and cloned a 484 bp cDNA fragment that corresponds to the 3' end of rat glycogenin [4].
• In addition, the nucleotide and amino acid sequences of rat glycogenin may be used to investigate the physiological and pathophysiological roles of glycogenin in rat tissues [4].

Anatomical context of Gyg1

• No limiting role for glycogenin in determining maximal attainable glycogen levels in rat skeletal muscle [5].
• The effect of increasing the glycogenin level on glycogen synthesis was studied in rat 1 fibroblasts stably overexpressing rabbit muscle glycogenin [6].

Associations of Gyg1 with chemical compounds

• The following conclusions have been drawn: 1) In the ammonia-treated astrocytes starved of glucose, free glycogenin is present [1].
• Analysis of [14C]glucose- or [35S]methionine-labeled extracts from glycogenin-expressing cells by continuous polyacrylamide gel electrophoresis and by two-dimensional gel electrophoresis revealed a continuum of glycogenin-containing species from low molecular mass to sizes significantly greater than 400 kDa [6].
• In fasted rats, glycogenin was present predominantly as the free-form of the enzyme, i.e., not attached to an amylase-digestible glycan, presumably glycogen [7].

Analytical, diagnostic and therapeutic context of Gyg1

• Molecular cloning and developmental expression of rat glycogenin in cardiac tissue [4].
• Immunofluorescence analysis revealed a diffuse cytoplasmic distribution of glycogenin expressed in rat 1 cells [6].
• In the presence of glucose, all of the expressed glycogenin was attached to polysaccharide and the free protein could only be detected by western blot analysis after incubation of cells in a glucose-depleted medium or treatment of the cell extract with alpha-amylase [6].

References