Which apolipoprotein activates LCAT and is a structural protein for HDL?

Apolipoprotein A-I (ApoA-1) plays a crucial role in lipid metabolism and is a key component of high-density lipoprotein (HDL). It serves two primary functions in relation to HDL: it acts as a structural protein and activates lecithin-cholesterol acyltransferase (LCAT).

Firstly, ApoA-1 is the main protein that constitutes HDL, contributing to its structure and stability. HDL is often referred to as "good cholesterol" due to its role in reverse cholesterol transport, which involves carrying cholesterol away from peripheral tissues back to the liver for excretion.

Secondly, ApoA-1 activates LCAT, which is an enzyme critical for the maturation of HDL particles. LCAT catalyzes the esterification of free cholesterol on HDL, leading to the formation of cholesteryl esters. This process helps HDL acquire and transport more cholesterol, enhancing its function in reverse cholesterol transport and reinforcing cardiovascular health.

In summary, the involvement of ApoA-1 in both the structural integrity of HDL and in the activation of LCAT underscores its importance in lipid metabolism and cardiovascular health.