Lecture 13 (Part 3) - Metabolism of HDL Flashcards
What is the alternative name for the metabolism of HDL, and why is it considered beneficial?
The alternative name for the metabolism of HDL is “Reverse Cholesterol Transport.” It is considered beneficial or “good cholesterol” due to its protective effect against cardiovascular disease.
Describe the initial shape of HDL when released from the liver.
HDL is released in a discoidal shape.
How does HDL interact with tissues during reverse cholesterol transport?
HDL interacts with tissues through the ABCA1 receptor.
What role does LCAT play in the metabolism of HDL?
LCAT (Lecithin Cholesterol Acyltransferase) converts cholesterol into cholesterol esters, allowing it to be compartmentalized and reducing the concentration of free cholesterol. This enzyme removes cholesterol from non-hepatic tissues, where bile acids can be made, further reducing cholesterol in the system.
How does LCAT ensure that the diffusion gradient doesn’t switch during the conversion of cholesterol to cholesterol esters?
LCAT catalyzes the reaction to maintain the diffusion gradient, preventing the switch of cholesterol back to its free form.
What is the role of SR-B1 in the unloading of lipids from HDL?
SR-B1 (Scavenger Receptor Class B Type 1) binds to ApoE and ApoA1 and allows phospholipids, cholesterol, and cholesterol esters to be unloaded from HDL.
What happens to the HDL particle after unloading its lipids?
The HDL particle shrinks in size, completing the HDL cycle.
Why is HDL often referred to as “good cholesterol”?
HDL is often called “good cholesterol” due to its protective effect against cardiovascular disease and its role in reverse cholesterol transport, which helps remove excess cholesterol from peripheral tissues and transport it back to the liver for excretion.
