Biosynthesis of glycogen in Neurospora crassa. Existence of a glucoproteic intermediate in the initiation process.
A soluble enzyme preparation (20,000 X g supernatant fraction), prepared from the mycelia of wild-type Neurospora crassa, was capable of transferring [14C]glucose from UDP-[14C]glucose into both trichloroacetic acid (TCA)-soluble and TCA-insoluble macromolecule products in the absence of added primer. These reactions did not require either high concentrations of salts or any other chemical reagents. Two labeled products were formed; one was a glycogen-like polysaccharide and the other was a glycoprotein with glucosyl chains bound to protein through an acid-labile bond. After mild treatment of the glucoprotein with acid, the product liberated from the protein behaved as a mixture of malto-oligosaccharides and alpha-1,4-glucan with branches. The carbohydrate moiety of the glucoprotein seemed to be released upon prolonged incubation with the enzyme preparation. The glucan thus liberated from the glucoprotein may serve as a primer for the glycogen synthase. The results obtained are therefore suggestive of the existence of a glucoproteic intermediate in the initiation of glycogen biosynthesis.
D002241:Carbohydrates / Q000032:analysis; D002413:Cations, Divalent; D002455:Cell Division; D005964:Glucosyltransferases / Q000378:metabolism; D006003:Glycogen / Q000096:biosynthesis*; D006023:Glycoproteins / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009491:Neurospora / Q000378:metabolism*; D009492:Neurospora crassa / Q000378:metabolism*; D013696:Temperature
D002241:Carbohydrates; D002413:Cations, Divalent; D006023:Glycoproteins; D006003:Glycogen; D005964:Glucosyltransferases