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Figure, 21-23 Head group attachment Membrane phospholipids: Glycerophospholipids sphingolipids Backbone Glycerol, sphingosine (serine) Fatty acid ( Phosphatidic acid, DAG) Hydrophilic head Exchange head group Smooth ER Mitochondria inner membrane
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Figure, 21-24 Two strategies for forming phosphodiester bond
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FIGURE 21–25 Origin of the polar head groups of phospholipids in E
FIGURE 21–25 Origin of the polar head groups of phospholipids in E. coli. p.826
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p.826
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Figure, 21-26 Polar head in eukaryotes Kinase-- Signal transduction Mitochondria inner membrane Help enzymes for energy metabolism --complex IV and V, apoptosis (cytochrome C release)
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Figure, 21-27 Yeast (Eukaryotic cells –major source of PE and PC)
PS PE p.828
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Figure, 21-27 PC p.828 S-adenosylmethionine (SAM)
S-adenosylhomocysteine PC p.828
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Fig. 21-28 a head group exchange (only in mammals—ER)
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Figure, b Phosphatidylcholine in mammals PE (the same strategy) Salvage pathway Choline reused (strategy 2)
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p.829 Figure, 21-29 summary of the pathways
for synthesis of major phospholipid Mutation in ethanolamine kinase (easily shocked) Eliminate phosphatidylethanolamine Synthesis: less in membrane Transient paralysis: electrical stimulation In liver only In mammals (no CDP-diacylglycerol and serine to PS) p.829
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Figure, 21-30 Ether lipid, Plasmalogen platelet-activating factor Half of the heart phospholipid
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Head group
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peroxisome
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Figure, 21-31 Sphingolipids 2nd big group Lung surfactant
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O- Step 1 18 C amine
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Step 2 (SER) Step 3 Step 4 Glycolipid Glycosidic linkage
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Golgi
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Figure, 21-32 Not required in diet Cell membrane Steroid hormone Bile acids
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Figure, 21-33 Cholesterol biosynthesis In liver condensation 6C 5C polymerization 30C cyclization
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Figure, 21-34 Synthesis of mevalonate cytosol Rate-limiting step Release 3CoA (membrane of the SER)
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Figure, 21-35 Mevalonate to activated isoprene Use 3 ATP Release 1 CO2
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Figure, 21-36 Squalene 10C 15C 30C
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(rose oil)
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Figure, 21-37 Ring closure Mixed function oxidase plants 20 steps Methyl group migration and removal
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Figure, 21-38 Cholesteryl esters Stored or in lipoprotein particles
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Figure 21-39 Plasma Lipoproteins- Lipid transport (LDL)
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Figure 21-39B
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TABLE 21-1 p.836
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TABLE 21-2 p.837
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Figure21-40 Lipoprotein and Lipid transport apoA-I apoB100 apoE apoB100 apoCII--lipase
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Figure 21-42 Uptake of cholesterol by receptor-mediated endocytosis
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Figure21-40 Lipoprotein and Lipid transport apoA-I SR-BI ABC1
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Chylomicron and VLDL remnants
Figure 21-41 Chylomicron and VLDL remnants Surface of nascent HDL
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Figure, 21-44 Regulation of cholesterol dp p Inhibit transcription
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Figure, 21-43 SREBP (sterol regulatory element-binding protein) activation SCAP: SREBP cleavage-activating protein— binds to cholesterol and other sterols HMG CoA reductase LDLR
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statin Figure, 21-45 Inhibitors of HMG-CoA reductase
Cholestyramine-resin binds to bile acids -prevent reabsorption Competitive inhibition of HMG-CoA reductase statin
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Figure, isoprenoid Prenylation Proetins are anchored to cellular membrane
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Figure, 21-46 Steroid hormones from cholesterol Increase gluconeogenesis And TAG cycle
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Figure, 21-47 Side chain cleavage Adrenal cortex mitochondria Hydroxylation and cleavage
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Fatty liver: TAG formation and export imbalance Extensive accumulation of TAG—cirrhosis Free fatty acids increase in plasma, then to liver accumulation Block production of plasma lipoproteins a. apolipoprotein synthesis b. lipoprotein c. phospholipid d. secretory pathway Ethanol—fatty liver Ethanol is converted to be acetaldehyde by alcohol dehydrogenase and NADH is produced Excess NADH inhibit CAC and increase lipogenesis (cholesterol)
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FIGURE 10-18 Arachidonic acid and some eicosanoid derivatives
FIGURE Arachidonic acid and some eicosanoid derivatives. Arachidonic acid (arachidonate at pH 7) is the precursor of eicosanoids, including the prostaglandins, thromboxanes, and leukotrienes. In prostaglandin E1, C-8 and C-12 of arachidonate are joined to form the characteristic five-membered ring. In thromboxane A2, the C-8 and C-12 are joined and an oxygen atom is added to form the six-membered ring. Leukotriene A4 has a series of three conjugated double bonds. Nonsteroidal antiinflammatory drugs (NSAIDs) such as aspirin and ibuprofen block the formation of prostaglandins and thromboxanes from arachidonate by inhibiting the enzyme cyclooxygenase (prostaglandin H2 synthase). 45
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Homework: How insulin regulates lipid metabolism?
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