Second Messengers

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Second Messengers
2013-05-07 16:01:25
BIO 220

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  1. More than __ hormones identified in humans.
  2. Many hormones require __; __ do not
    • second messengers
    • steroid hormones
  3. Steroid Hormones and Gene Expression
    • Pass through target cell membrane and bind to a receptor protein in
    •   the nucleus.
    • -  Hormone receptor complex binds to specific sites (acceptor protein)   along chromatin to activate gene expression.
    • -  Two cell types can respond differently to same steroid   hormone since acceptor proteins associated with different genes
  4. Peptide Hormones And Hormones Derived From Amino Acids   Work By __
    What are they?
    • Second Messengers:
    • Cyclic AMP (cAMP)
    • Inositol Triphosphate
  5. Explain cAMP
    - what it stands for?
    -made by?
    - activates
    - what that does
    - effect?
    • adenosine 3',5'-cyclic monophosphate
    • -  synthesized from ATP by adenylate cyclase
    • -  activates protein kinase A (PKA)
    • -  PKA phosphorylates target proteins producing cellular   response.
    • -  hydrolyzed/brokendown by phosphodiesterase (PDE)
  6. What is the g-protein pathway if epinephrine initiates the signal?
    • Epinephrine binds to G protein- coupled receptor, causing G protein to convert GTP to ATP and also activate adenylyl cyclase.
    • Adenylyl cyclase will convert ATP to cAMP, which activatse protein Kinase A and causes a response.
  7. Membrane Lipid System (__)
    • IP3 and DAG
    • IP3 (inositol triphosphate)
    • -  DAG (diacylglycerol
  8. What is the cascade, part 1 and 2?
    • Phosphatidylinositol (PI): phospholipid present in inner membrane.
    • -  PI phosphorylated to (2-steps) to phosphatidylinositol-4,5-  bisphosphate (PIP2)
  9. What is the cascade, parts 3 and 4?
    • PIP2 cleaved by phospholipase C to produce IP3 and DAG (Note:   phospholipase C activation is G-protein mediated)
    • -  IP3 water soluble, diffuses into cytoplasm, binds to receptors on ER   stimulates release of Ca2+.
  10. What is the cascade, parts 5 and 6?
    • Ca2+ activates calmodulin kinase.
    • -  DAG activates Protein Kinase C (PKC).