Biochem 501: Lecture 29: Biological Activity of Lipids

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Biochem 501: Lecture 29: Biological Activity of Lipids
2013-11-12 19:24:35
Biochem 501

Biochem 501
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  1. Phosphoinositide cascade generates which second messengers
    Diacylglycerol (DAG) and Inositol triphosphate (IP3)
  2. DAG is an activator for?
    Protein kinase C
  3. IP3 causes release of?
    Ca2+, 3rd messenger from intracellular stores
  4. Steroid hormones produce effects how
    directly binding and inducing transcription of genes
  5. Eicosanoids
    • 20 carbon unsaturated fatty acids derived from arachidonic acid
    •        -Arachidonic acid derived from linoleic acid, essential fatty acid
    • Hormone-like biomodulator substances
  6. Types of lipids
    Storage, Membrane Lipids, Hormones, Fat Soluble Vitamins, Bile acids, Waxes, Pigments, Scents, ect.
  7. Types of Storage Lipids
    Neutral Fat: Triacylglycerols
  8. Membrane Lipids
    Polar Lipids: Phospholipids, Glycolipids, Sphingolipids, Sterols
  9. Types of Hormone Lipids
    Steroids, Prostaglandins
  10. Types of Fat Soluble Lipids
    A, D, K
  11. PIP2 is cleaved into what
    DG and IP3
  12. Phosphoinositide cascade Step 1
    • Hormone binds to receptor
    • GDP bound to GP to become GTP
  13. Phosphoinositide cascade Step 2

    GTP bounded GP moves to Phospholipase C (PLC) and activates it
  14. Phosphoinositide cascade Step 3
    • Active PLC cleaves PIP2 into IP3 and DG
  15. Phosphoinositide cascade Step 4

    IP3 binds to a specific receptor on ER, releasing Ca2+
  16. Phosphoinositide cascade Step 5
    • DG and Ca2+ activate PKC on plasma membrane
  17. Phosphoinositide cascade Step 6
    • PKC phosphorylates cellular proteins, producing the response to the hormones
  18. Effects mediated by Phosphoinositide cascade
    • Glycogenlysis in liver
    • Histamine secretion of mast cells
    • Serotonin release by blood platelets
    • Smooth muscle contraction
    • Visual transduction in invertebrate photo-receptors
    • Insulin secretion by pancraetic islet cells
    • ect.
  19. Steroid hormone formation
  20. Cortisol
    • -Affects protein and carbohydrate metabolism
    • -Suppresses immune response, inflammation, and allergic responses.
  21. Aldosterone
    • Regulates re-absorption of
    • Na+, Cl-, HCO3- in the kidney
  22. Testosterone/Estradiol
    • -Male and female sex hormones.
    • -Influence secondary sexual characteristics.
    • -Regulate female reproductive cycle.
  23. Other Steroid Hormones
  24. Steroid Hormone Receptors share?
    Substantial sequence homology/functional domain substructure
  25. Model for Steroid Receptor Action
    • Serum binding protein carries hormone to plasma membrane
    • Steroid enters cell, enters nucleus
    • Steroid binds receptor on DNA, prompts transcription of mRNA
    • Translation into new protein
  26. Examples of specificity of steroid receptor binding in design of drugs
    • Progesterone vrs. RU 486
    • • RU 486 has similar structure as
    • progesterone
    • • It is used as an antagonist of
    • progesterone in early termination of pregnancy
    • Estrogen vs Tamoxifen
    • • Tamoxifen has similar structure as estrogen
    • • It competes with estrogen in binding to the estrogen receptor, but the tamoxifen receptor complex is inactive in gene regulation.
    • The cancer cells that depend on estrogen for growth will be killed off. So tamoxifen is used in the treatment of breast cancer in humans.
  27. Vitamin D is derived from what?
  28. Vitamin D is a precursor to what
    Hormone essential in calcium/phosphate metabolism
  29. Sources of Vitamin D3
    Formed in skin in reaction driven by UV light, in fish oils and as an additive in commercial milk
  30. Active form of Vitamin D
  31. Vitamin D deficiency leads to
    Defective bone formation, aka rickets
  32. Vitamin D formation pathway
  33. Eicosanoid Formation Pathway
  34. Functions of Eicosanoids
    The inflamatory response

    Regulation of pain and fever

    Regulation of blood pressure

    Induction of blood clotting

    Control of reproductive functions

    Regulation of the sleep-wake cycle

    Short lived, target nearby cells