Question 1

Question

A research team discovers a novel bacterial toxin that causes severe hypotension in infected patients. In vitro studies show the toxin ADP-ribosylates a specific amino acid on Gq alpha subunits, preventing their activation by GPCRs. Patients develop hypotension despite elevated levels of vasopressin, angiotensin II, and endothelin-1. Synthesize the pathophysiological mechanism explaining why multiple vasopressor hormones fail to maintain blood pressure in these patients.

Accepted Answer

ADP-ribosylation of Gq prevents PLC activation, blocking IP3-mediated calcium release and vascular smooth muscle contraction

Answer

The toxin depletes intracellular ATP preventing myosin-actin interaction

Answer

The toxin prevents receptor binding of vasopressor hormones through allosteric inhibition

Answer

ADP-ribosylation increases cAMP levels causing smooth muscle relaxation

Answer

The toxin activates Gi proteins causing excessive vasodilation that overwhelms vasoconstrictor signals

Signal transduction pathways — MCQs

Signal transduction pathways — MCQs

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