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Histamine binds to the H1 G-protein-linked receptor to initiate the itchiness and airway constriction associated with an allergic response. If a mutation in the associated G-protein’s alpha subunit prevented the hydrolysis of GTP, how would the allergic response change?

a) It would intensify the allergic response
b) It would weaken the allergic response
c) It would have no effect on the allergic response
d) It would completely stop the allergic response

1 Answer

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Final answer:

A mutation in the G-protein's alpha subunit that prevents GTP hydrolysis would likely result in a more severe allergic response due to prolonged signal activation.

Correct option is

a) It would intensify the allergic response

Step-by-step explanation:

The allergic response involves a series of reactions within the immune system, particularly the release of histamine after the binding of an allergen to IgE-primed mast cells. In normal circumstances, histamine binds to the H1 G-protein-linked receptor, triggering pathways that lead to symptoms such as itchiness and airway constriction. If a mutation occurs in the associated G-protein's alpha subunit that prevents the hydrolysis of GTP, the resulting effect would be a prolonged activation of the G-protein and a continuous signaling. This would mean that the allergic response, instead of being a transient event, could potentially become more severe versus normal signaling because the signal would not be properly terminated.

Antihistamines work by competing with histamine for the H1 receptor, which helps to alleviate symptoms by preventing the histamine from binding and initiating its effects, thus helping to restore homeostasis during an allergic reaction.

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