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What is glycogen synthase activated and inhibited by?
What about glycogne phosphorylase (3,3)
Insulin, glucagon
Glucagon, AMP, Ca2+. Insulin (PP1), glucose ATP
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ALT - what does it do?
Transfers a-amino group from alanine to a-ketoglutarate to form pyruvate and glutamate.
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AST - what does it do?
Transfers amino group from glutamate to OAA forming aspartate.
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Glutamate dehydrogenase
Glutamate --> a-ketoglutarate + free NH3
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What regulates the urea cycle? (4)
Activated by high protein diet, starvation (upregulates autophagy and urea cycle enzymes), high protein meal with arginine (activates N-acetylglutamate which activates CPS-1)
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In lipoproteins, what does APOCII do? LPL? ABC transporters? LCAT? CETP? ACAT? ApoE? Can ApoB48 bind to LDL-R?
- APOCII activates LPL (activated by insulin).
- LPL = lipoprotein lipase - hydrolyzes TAGs in chylomicrons & VLDL for uptake into cell (increased in pregnant womenin 3rd trimester & cancer patients
- ABC transporters - Help HDL remove free cholesterol from plasma mebranes of peripheral tissues to return to liver.
- LCAT - Esterifies cholesterol --> CE in HDL Activated by ApoA2
- CETP - cholesterol ester transfer protein - transfers TAGs.
- ACAT - esterifies CE within cell. Activated when cell levels of cholesterol are high
- ApoE - ligand for binding IDL, LDL to LDL-R and LRP
- No. Needs help from ApoE.
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HMG CoA Reductase
Activated by (2)
Inhibited by (4)
Activates? (2)
Activated by low levels of sterols --> SREBP2 and insulin.
Inhibited by glucagon, AMPK, cholesterol feedback, and statin drugs.
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Succinyl CoA acetoacetate transferase
Activates acetoacetate into its active form (acetyl CoA) for use in peripheral tissues. Not found in liver!
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How is ketone body formation regulated?
Emzyme Activated by? (2) Inhibited by? (4)
- 1. Magnitude of lipolysis (amount of FAs released from adipocytes)
- 2. CPT-1 and entry of acetyl CoA into mitochondria
- 3. Entry of acetyl CoA --> TCA cycle (lack of entry increases substrates for ketone body formation)
- 4. HMG CoA reductase activated by SREBP-2 and insulin.
- 5. Inhibited by glucagon, AMPK, cholesterol (feedback inhibition) and statin drugs.
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