You are studying the activities of a compound that is purported to be an inhibitor of the antioxidant functions of HDL. Administration of this compound to experimental animals does indeed result in elevated levels of oxidized LDL (oxLDL) in the plasma. Which of the following proteins is the most likely target of this compound accounting for the reduced antioxidant function of HDL?

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Quizplus · Accepted Answer

ApoA-I is a major protein component of HDL and plays a crucial role in its antioxidant functions. Inhibition of apoA-I would impair HDL's ability to prevent LDL oxidation, leading to elevated levels of oxidized LDL. Numerous lines of evidence demonstrate that apoA-I is a major antiatherogenic and antioxidant factor in HDL due to its critical role in the HDL-mediated process of reverse cholesterol transport. In addition to reverse cholesterol transport, apoA-I can remove oxidized phospholipids from oxidized LDLs (oxLDLs) and from cells. Specific methionine residues (Met112 and Met148) of apoA-I have been shown to directly reduce cholesterol ester hydroperoxides and phosphatidylcholine hydroperoxides.

You Are Studying the Activities of a Compound That Is