Platelet-activating factor (PAF) causes release of arachidonic acid from membrane lipids. Which of the following enzymes is most likely responsible for this effect?
A) cyclooxygenase
B) lipoprotein lipase
C) lipoxygenase
D) phospholipase A2
E) thromboxane synthase

Question

Quizplus · Accepted Answer

Phospholipase A2 is the enzyme responsible for releasing arachidonic acid from membrane phospholipids, which is a key step in the production of eicosanoids.  Arachidonic acid is found esterified to the sn2 position of the glycerol backbone of membrane phospholipids. Activation of membrane receptors, such as that which is activated by PAF, leads to activation of phospholipase A2, which hydrolyzes the ester bond at the sn2 position in phospholipids.

Platelet-Activating Factor (PAF) Causes Release of Arachidonic Acid from Membrane