Structural and functional studies on rabbit liver glycogenin.
Glycogenin, the protein primer required for the biogenesis of muscle glycogen, has been isolated from rabbit liver glycogen. The protein comprised 0.0025% of liver glycogen by mass, 200-fold lower than the glycogenin content of muscle glycogen. Structural analyses, including determination of the amino acid sequence surrounding the glucosylated-tyrosine residue, showed identity with muscle glycogenin. Catalytically active liver glycogenin was partially purified and, like the skeletal muscle protein, catalysed an intramolecular, Mn2+- and UDP-Glc-dependent autoglucosylation reaction, forming a primer on which glycogen synthase could act. The results demonstrate that hepatic and muscle glycogenins are almost certainly identical proteins and that liver and skeletal muscle share a common mechanism for the biogenesis of glycogen molecules. The results also indicate that there is about one glycogenin molecule/liver glycogen alpha particle.
Smythe
C
C
Department of Biochemistry, University of Dundee, Scotland.
Villar-Palasi
C
C
Cohen
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P
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004563:Electrochemistry; D004591:Electrophoresis, Polyacrylamide Gel; D005964:Glucosyltransferases / Q000378:metabolism; D006023:Glycoproteins / Q000302:isolation & purification*; D006868:Hydrolysis; D008112:Liver Glycogen / Q000032:analysis*; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000302:isolation & purification*; D010446:Peptide Fragments / Q000032:analysis; D011817:Rabbits; D014357:Trypsin
D000596:Amino Acids; D006023:Glycoproteins; D008112:Liver Glycogen; D009124:Muscle Proteins; D010446:Peptide Fragments; C051887:glycogenin; D005964:Glucosyltransferases; D014357:Trypsin