• Glycogen
  • Branches have α-(1,6) bonds; linkages have α-(1,4) bonds.
• Skeletal muscle
  • Glycogen undergoes glycogenolysis → glucose-1-phosphate → glucose-6-phosphate, which is rapidly metabolized during exercise.
• Hepatocytes
  • Glycogen is stored and undergoes glycogenolysis to maintain blood sugar at appropriate levels.
    • Glycogen phosphorylase (4) liberates glucose-1-phosphate residues off branched glycogen until 4 glucose units remain on a branch.
    • Then 4-α-d-glucanotransferase (debranching enzyme[5]) moves 3 of the 4 glucose units from the branch to the linkage.
    • Then α-1,6-glucosidase (debranching enzyme [6]) cleaves off the last residue, liberating glucose.
  • “Limit dextrin” refers to the one to four residues remaining on a branch after glycogen phosphorylase has already shortened it.
  • Note: A small amount of glycogen is degraded in lysosomes by α-1,4-glucosidase (acid maltase).