SURVEY OF BIOCHEMISTRY Glycogen Synthesis and Control

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SURVEY OF BIOCHEMISTRYGlycogen Synthesis and
Control
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4 Enzymes in Glycogen Synthesis

• UDP-Glucose Pyrophosphorylase
• Glycogenin
• Glycogen Synthase
• Glycogen Branching Enzyme

Draw how this works
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UDP-Glucose Pyrophosphorylase
UDP-GlucosePyrophosphorylase activates
glucosylunits
PPi
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Glycogenin

• Glucose residues cannot just link together
  without aid
• Glycogenin activity
• Transfers glucose from UDP-glucose to itself
• Creates glycogen primer

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Glycogen Synthase
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Glycogen Branching Enzyme
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Review of Glycogen Breakdown

• Glycogen Phosphorylase
• Makes Glucose 1-Phosphate
• Phosphoglucomutase
• Converts G1P to Glucose 6-Phosphate
• Glycogen Debranching Enzyme
• Transfers limit branch to main chain
• Cleave off remaining glucose from branch

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Overview
How are these processes controlled?
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Control

• Allosteric Control
• Control via Covalent Modification
• Binding of Ca2
• Phosphorylation (typically activation)
• Dephosphorylation (typically inactivation)
• Hormonal Control
• Insulin
• Glucagon

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Covalent ModificationsGlycogen Phosphorylase
Focus on Phosphorylase Kinase
Glycogen phosphorylaseparticipates in glycogen
breakdown
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Hormonal Control