Reverse cholesterol transport - all are
true except-
a) Transport of cholesterol from extrahepatic tissues to liver
b) ATP Binding Cassette Transporter protein is involved in the
conversion of HDL3 to HDL2
c) Lecithin Cholesterol Acyl Transferase helps in the
conversion of Spheroidal HDL to Discoidal HDL
d) Cholesterol Ester Transfer Protein helps in increasing HDL
level
Correct Answer - D
Ans. is ‘d’ i.e., Cholesterol Ester Transfer Protein helps in
increasing HDL level
Reverse Cholesterol Transport is the transport of Cholesterol ester
and phospholipid from extrahepatic tissues to liver.
HDL is released by both liver and intestinal cells.
In both the cases, they are released as discoidal HDL
Apo Al activates Lecithin Cholesterol Acyl Transferase and it
converts discoidal HDL to Spheroidal HDL (HDL3)
HDL3 activates ABC1 (ATP Binding Casette Transporter 1) to collect
cholesterol and phospholipids from extra hepatic tissue membranes.
This way HDL3 size increases and density decreases. Hence it
forms HDL2.
This HDL2 reaches liver to empty its contents into liver.
On the way to liver, if HDL2 encounters IDL, Cholesterol Ester
Transfer Protein (CETP) transfers Choelsterol ester from HDL2 to
IDL, converting IDL to LDL. Hence CETP decreases HDL level and
increases LDL level.