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29 Cards in this Set
- Front
- Back
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What are the 3 secondary messenger mechanisms we covered?
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Changes in:
- [cAMP] & [cGMP] - [IP3] - [Ca2+] |
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What does IP3 stand for?
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Inisitol triphosphate
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What are the three kinds of receptor proteins we covered?
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G-protein coupled receptors (GPCRs), Tyrosine receptor kinases (TRKs), and Cytoplasmic/Nuclear receptors
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What does GPCR stand for?
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G-protein coupled receptor
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What does TRK stand for?
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Tyrosine receptor kinase
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What is the overall structure of a GPCR?
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A serpentine protein that crosses the cellular membrane 7 times.
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How many subunits make up a g-protein?
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3
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How does a GPCR interact with a g-protein?
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When it binds a receptor, the GPCR activates the g-protein, tacking on a GTP in place of GDP, causing a shift in the orientation of the 3 subunits.
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What does an activated g-protein do?
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Activates the enzyme adenylate cyclase.
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What does adenylate cyclase do when activated?
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Makes cAMP from ATP
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What chemical change occurs when a g-protein is activated?
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A bound GDP is pushed off by GTP
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After being produced by adenylate cyclase, what does cAMP do?
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Trigger the production of ADP by phosphorylase kinase
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What does ADP do in response to the signal cascade from a GPCR?
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Act as a transcription factor.
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How is an activated g-protein deactivated?
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GDP comes in and pushes the activating GTP off.
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What are the 3 g-protein isoforms?
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Gi, Gs, and Gq
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What does the Gi g-protein isoform do?
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Decreases [cAMP]
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What does the Gs g-protein isoform do?
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Increases [cAMP]
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What does the Gq g-protein isoform do?
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Increases [Ca2+]
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How does the Gq g-protein isoform change [Ca2+]?
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It activates phospholipase-C, which releases IP2, which opens Ca2+ gates on the smooth ER.
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What enzyme degrades cAMP to stop the affects of an active GPCR?
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Phosphodiesterase (PDE)
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What drug targets phosphodiesterase, resulting in an "always on" state in a particular tissue?
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Viagra
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To what effect does a Gq g-protein increase [Ca2+]?
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The activation of protein kinase transcription factors.
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How do tyrosine receptor kinases work?
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The signal molecule binds to the TRK, which activates the internal protein components, which propagate the signal.
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Where are cytoplasmuc/nuclear receptors located?
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Within the cytoplasm, or the nucleus
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What sort of signal molecule works with cytoplasmuc/nuclear receptors?
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Things that can pass through the cell membrane.
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What are some examples of cytoplasmic/nuclear receptor signaling molecules?
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Estrogen
Retinoic acid Thyroid hormone |
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What is the major means of sensitivity modulation in cells?
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Upregulation or downregulation of receptors
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How are receptors up/downregulated?
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De/phosphorylation
Change in receptor numbers |
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What protein is used to trigger the endocytosis of GPCRs?
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Arrestin
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