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7 Cards in this Set

  • Front
  • Back

Regulatory Strategies

Allosteric Control

Multiple forms of Enzymes

Reversible covalent modifications

Proteolytic Activation

Control of the amount of protein present

Multiple Forms of Enzymes: Phosphoprotein Proteases 2A (PP2A)

Catalytic subunit has 2 Mg2+ ions on its active site

These are near the substrate recognition site

PDB ID 2NNP is the regullatory subunit

Microcystin-LR is a specific inhibitor of PP2A

PP2A recognises several target proteins, its specificity is provided by a regulatory subunit

Different subunits can fit with the scaffold unit to create unique substrate-binding sites

Control the Amount of Protein Present: PEP Carboxykinase Promoter Region

FOXO1 (transcription factor): Degraded under Insulin Receptor Activation thus reducing levels of PEP carboxykinase

CREB (transcription factor): Activated by cAMP pathway which happens when glucagon is releases

PEP Carboxykinase involved in gluconeogenesis

Control the Amount of Protein Present: Glycogen Synthesis and Degradation

Involves glycogen synthase and glycogen phosphorylase

Amount of substrates is regulated

Whole process is tightly regulated via:

-Use of different enzymes in both pathways

-Insulin dephosphorylating glycogen phosphorylase and glycogen synthase

-Glycagon or adrenaline phosphorylates them

Allosteric Regulation: Glycogen Phosphorylase

Glucose, Glucose-6-P


Insulin dephosphorylates Phosphorylase a

Double regulation both hormonally and allosterically

Allosteric Regulation: Glycogen Synthase Kinase 3

Active when dephosphorylated

Insulin increase glycogen synthase activity by encouraging dehosphorylation and inhibiting phosphorylation

Glucagon inhibits

Glucose and Glucose-6-phosphate increase

Phosphorylation happens at Serine residues by GSK3

Allosteric Regulation: FA Oxidation and Synthesis

When biosynthesis is active oxidation is inhibited via:

-Action of malonyl CoA over carnitine acyl transferase I

-Action of PPAR's

-Role of Hormones

-Action of palmitoyl CoA