[studytogether]

is cholesterol in lipoprotein esterified?
I see some statements says that cholesterol in lipoprotein is esterified.
I wonder is all cholesterol in lipoprotein are esterified?

thx 4 teaching

[AhmedEzatAlzawalaty]

yes there is free cholesterol and cholesteryl esters in lipoproteins

[DocSuleman]

Brother!

The main transporting vehicle for cholesterol is HDL ( High density lipoprotein). Here I'm going to explain its metabolism then you will come to know about the cholesterol chemical form in it!

when HDL is synthesized by liver it contains

Apoproteins (A1 + others) + Free Cholestrol + LCAT + Phospholipids

LCAT = lecithing cholestrol acyl transferase


This newly synthesized HDL is called nascent HDL.

the action of LCAT converts nascent HDL into HDL₃. How?
simply as name indicate it transfer ACYL group from phospholipids to cholestrol and ESTERIFIED IT. and the resulting HDL is termed as HDL₃. (Note: A1 works as cofactor for LCAT)

HDL₃ = Apoproteins (A1 + others) + ESTRIFIED Cholestrol + LCAT + Phospholipids


this HDL₃ take more unsestrifed cholesterol from other tissue of bodies esterified it by LCAT and convertes to HDL₂. which in turn release its cholesterol to liver and gain converts into HDL₃ and the cycle repeats.

Simply it determines the  stage of metabolism of HDL that cholesterol will be esterified or not!