Fatty Acid Storage and Breakdown Flashcards
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What are the three sources of TAGs?
- Dietary TAG (Intestinal cells)
- De Novo TAG -n Hepatocytes
- De Novo TAG in Adipocytes
What extracellular factors stimulates the breakdown of TAGS?
- Glucagon
- Epinephrine
- Hunger and Exercise
Describe the signaling cascade for activation of TAG breakdown.
Hormone -> GPCR
GPCR -> ATP -> cAMP
cAMP -> PKA -> Activation of Perilipin and HS Lipase
Perilipin -> Activation of ATGL
What enzyme catalyzes the conversion of TAG to DAG?
Adipose triglyceride lipase (ATGL)
What enzyme catalyzes the conversion of DAG to MAG?
Hormone Sensitive Lipase
What enzyme catalyzes conversion of MAG to glycerol and Fatty Acids?
MAG lipase
What is Perilipin and how does it work?
- Family of proteins which coat lipid droplets
- Regulate lipolysis by controlling physical access to breakdown.
What is the process of phase I of Fatty Acid breakdown?
- In cytosol, addition of CoA to FA using ATP to enter intermembrane space
- Carnitine replaces CoA on FA and entrance into matrix
- Carnitine replaced by CoA in matrix
What occurs during Phase II of FA breakdown?
Beta Oxidation:
Fatty Acyl CoA —> Acetyl Coa + FADH2 + NADH
- Generates Ketone Bodies or ACetly CoA for TCA Cycle
What happens in the first reaction of Phase I of FA Breakdown?
Acyl Synthetase traps FA in cell makes it metabolically active by Adding CoA. Creates Thioester bond.
What are the four steps of Beta Oxidation?
- Oxidation by Acyl CoA dehydrogenase. Produces FADH2 for ETC
- Hydration by Enol CoA hydratase
- Oxidation by 3-hydroxyacyl CoA dehydrogenase. Forms NADH for ETC
- Thiolysis by Acetyl CoA Acetyltransferase (B-ketothiolase)
What is the NET ATP produced by the breakdown of Palmitate?
- FADH2 7 X 2 = 14 ATP
- NADH : 7 x 3 = 21 ATP
- Acetyl CoA : 8 x 12 = 96 ATP
- Total = 131
- ATP used: 2 (during activation of palmitate)
- NET ATP = 129
Where are Ketone bodies produced?
ONLY LIVER
