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26 Cards in this Set
- Front
- Back
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How many subunits does the G protein contain?
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3. Heterotrimeric.
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How many transmembrane segments are in the g protein coupled receptor?
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7
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Flow chart of G protein receptor
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Ligand bind to GPCR -> G protein associates -> GDP exchange for GTP -> alpha subunit runs over to enzyme, i.e., AC -> cAMP made -> GTP is hydrolyzed -> alpha reassociates
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REVIEW: what does cAMP do?
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Activates PKA
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3 types of G proteins and their major function
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Gs - stimulates production of cAMP
Gi - inhibits production of cAMP Gq - men's magazine. just kidding. Activates phospholipase C, rise in intrac Ca, activates PKC |
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What does activation of all beta-receptor types do?
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Increases cAMP
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What does activation of an alpha 2-receptor type do?
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Decreases cAMP
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What does activation of an alpha -1-receptor type do?
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Increases PKC
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Gs
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ALL BETA
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Gi
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alpha 2
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Gq
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alpha 1
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What effect does PKA have in skeletal muscle?
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Breakdown of glycogen
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What effect does PKA have in cardiac muscle?
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Contraction
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Name the enzyme that breaks down cAMP
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phosphodiesterase
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What is an IP3 receptor?
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A calcium channel
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The three control mechanisms for intracellular Ca
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1. Ca-ATPase
2. Ca-binding molecule (calsequestrin, for example) 3. Mitochondrial storage |
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Phenylephrine
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a-1 receptor agonist
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Isoproterenol
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B-1 receptor agonist
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Albuterol
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B-2 receptor agonist
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Propanolol/Metoprolol
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Beta blockers
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Phenoxybenzamine/Phentolamine/Prazosin
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alpha blockers
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Effects of cholera and pertussis toxins?
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Respectively stimulates Gs and inhibits Gi - same effect is radical increase in cAMP
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Characterize the two types of cGMP receptors
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Soluble: cytoplasmic, activated by NO (nitroglycerin) Particulate: membrane bound, activated by peptide hormones (ANP)
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cGMP does what?
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Activates PKG, which inhibits many elements of smooth muscle contraction. PKG=smooth muscle relaxation.
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How does paracrine signaling by NO work?
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Nearby cell manufactures and releases NO, which binds to heme in cGMP receptor, making cGMP.
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What famous drug inhibits the cGMP pathway in smooth muscle?
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Viagra.
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