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22 Cards in this Set
- Front
- Back
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What is the largest family of cell receptors?
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G protein linked receptors (GPLR)
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How does Vibrio Cholerae cause disease?
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Through the production of cAMP
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Describe the serpentine structure shared by all GLPR
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Seven hydrophobic stretches through the membrane with amine group in the ECM and the carboxy group in the cytosol.
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What is the function of trimeric G proteins?
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Serves as relay molecules for GPLR
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What does the alpha subunit of the trimeric G protein bind?
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Guanyl nucleotide
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What is the only subunit of trimeric G protein that does not bind to PM?
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Beta subunit
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Describe the inactive state of trimeric G proteins.
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GDP is bound to G alpha subunit, which is bound to G beta and G gamma. (Trimeric complex)
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Describe the active state of trimeric G proteins.
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GTP is bound on G alpha, while G beta and G gamma dissociate.
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What are the two "flavors" of trimeric G proteins?
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Gs - G stimulatory that acts to stimulate target enzyme
Gi - G inhibitory that acts to inhibit target enzyme |
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Trimeric G proteins functionally couple ________ to ________ to regulate production of ___________
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the receptor
adenylyl cyclase cAMP |
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What binds to adenylyl cyclase to activate synthesis of cAMP?
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Gs alpha
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How do you deactivate G hormone/receptor complex? 2 steps
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1. Carboxy terminal tail of the receptor becomes phosphorylated
2. Phosphorylated tail is bound by proteins (arrestins) which sterically block G protein/receptor interaction |
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What does hydrolysis of GTP do?
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Inactivate the trimeric G protein.
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What enhances the hydrolysis of GTP?
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RGS proteins (regulator of G protein signal)
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What does cAMP activate?
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PKA (protein kinase A)
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What are the two types of PKA and where are they?
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Type I - Free in the cytosol
Type II - anchored to membrane |
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In the nucleus, how does PKA activate transcription?
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PKA phosphorylates transcription factor CREB. The phosphorylated CREB will bind to co-activator CBP which will activate transcription.
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What is the only means of deactivating cAMP?
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Through the actions of PDE (cAMP Phosphodiesterases)
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What does PDE change cAMP into?
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5'-AMP
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Give two inhibitors of PDE.
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1. Xanthine (caffeine & theophylline)
2. Viagra |
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T/F - Adrenaline is mediated by cAMP
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True
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If blood calcium is low, what hormone is secreted?
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PTH
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