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Old 06-28-2011
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Question strongest signal by which receptor?

A research scientist is studying calcium fluxes in cultured cells using confocal laser scanning microscopy. The magnitude of the signal (brightness) is proportional to the strength of the calcium flux. Stimulation of which of the following receptor types would be expected to produce the strongest signal?

A. Alpha-1 adrenergic receptor
B. Beta-1 adrenergic receptor
C. Dopamine-1 receptor
D. Muscarinic acetylcholine receptor
E. Nicotinic acetylcholine receptor
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Old 06-28-2011
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I'd go with A.
(thinking that a1 receptors signal through the Gq receptors, leading to increased Ca2+ via the Phospholipase C- IP3 pathway).
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Old 06-28-2011
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correct answer is A
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Old 06-28-2011
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Alpha-1 receptors activate phospholipase C via the G protein Gq. Phospholipase C cleaves the membrane phospholipid phosphatidylinositol 4,5-bisphosphate to produce the products, inositol triphosphate (IP3) and diacylglycerol (DAG). IP3 releases intracellular calcium from the endoplasmic reticulum, and would therefore generate a robust signal. DAG activates protein kinase C.
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Old 07-02-2011
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....

Very good question.
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