A 23-year-old woman presents with low red blood cell count, corneal opacities, and renal insufficiency. She is diagnosed with lecithin:cholesterol acyltransferase (LCAT) ratio deficiency. In which of the following reactions LCAT is involved?
A) converting cholesterol to cholesterol esters
B) hydrolysis of HDL
C) promoting uptake of HDL into liver cells
D) transfer of cholesterol esters from HDL to VLDL
E) uptake of cholesterol from liver cells

Question

Quizplus · Accepted Answer

LCAT is an enzyme that catalyzes the conversion of free cholesterol into cholesterol esters, which are then incorporated into the core of lipoproteins like HDL.  The primary mechanism by which HDL acquires peripheral tissue cholesterol is via an interaction with macrophages in the subendothelial spaces of the tissues. The free cholesterol transferred from macrophages to HDL is esterified by HDL-associated LCAT. LCAT is synthesized in the liver and so named because it transfers a fatty acid from the C-2 position of lecithin to the C-3-OH of cholesterol, generating a cholesteryl ester and lysolecithin.

A 23-Year-Old Woman Presents with Low Red Blood Cell Count