A (1----4)-alpha-D-glucan-protein involved in liver glycogen biosynthesis.
A macromolecular (1----4)-alpha-D-[14C]glucan-protein complex was synthesized with a rat liver preparation and uridine diphosphate D-[14C]glucose. The size of the complex is contributed by both the protein and the (1----4)-alpha-D-glucosyl-oligomer components. Iodoacetamide treatment did not change the migration properties on Bio-Gel A-50m. Therefore, disulfide bonds linking glucan-protein subunits seem not to be involved. The [14C]glucan-protein, precipitated by diluted trichloroacetic acid, was digested by alpha-amylase, phosphorylase a, and proteases. The extent of proteolysis was greater for a complex having fewer D-glucose units incorporated. After proteolytic digestion of that complex, the labeled fragments behaved on electrophoresis, and ion-exchange and gel chromatography as [14C]glucosylated peptides. These findings support previous conclusions that the primer for liver glycogen synthesis is a protein on which glycogen is built up by covalent attachment.
D000818:Animals; D002250:Carbon Radioisotopes; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004590:Electrophoresis, Paper; D005936:Glucans / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism*; D008099:Liver / Q000201:enzymology; D008112:Liver Glycogen / Q000096:biosynthesis*; D051381:Rats; D014532:Uridine Diphosphate Glucose / Q000378:metabolism
D002250:Carbon Radioisotopes; D005936:Glucans; D006023:Glycoproteins; D008112:Liver Glycogen; D014532:Uridine Diphosphate Glucose