Lipoproteins are particles that contain a core of cholesterol and triglycerides surrounded by a membrane containing apolipoproteins. There are several main types of lipoproteins: chylomicrons and VLDL deliver triglycerides to cells, LDL delivers cholesterol to cells, and HDL transports excess cholesterol from cells back to the liver. The primary apolipoproteins are apoB in chylomicrons, VLDL, IDL, and LDL, and apoA1 in HDL.

1. LIPOPROTEINS
SOBIA RAFIQ
M.Phil. biochemistry

2. INTRODUCTION:
 Lipoproteins are basically a core full of fat and
cholesterol, along with a lipid membrane that
contains amphipathic proteins called Apo
lipoproteins.

3. TYPES OF LIPOPROTEINS:

4. LIPID AND PROTEIN CONTENT OF LIP-
PROTEINS:
 Apolipoprotein B is the
primary apolipoprotein
of chylomicrons, VLDL,
IDL, and LDL particles.
 While ApoA-1 is
present in HDL.

5. FUNCTION OF CHYLOMICRONS AND
VLDL:
 Chylomicrons and VLDL deliver TAG to cells in the
body. triglyceride-rich.
 Chylomicrons are synthesized by enterocytes VLDL
is synthesized in the liver.
 The function of these lipoproteins is to deliver
energy-rich triacylglycerol (TAG) to cells in the body
.
 TAG is stripped from both through the action of
lipoprotein lipase,
 an enzyme that is found on the surface of
endothelial cells.
 convert TAG to fatty acids and monoglycerides.
 Used by the body or stored.

6. LOW DENSITY LIPOPROTEINS:
 As VLDL particles are stripped of triacylglycerol,
These particles are remodeled at the liver and
transformed into LDL.
 Cells take up cholesterol by receptor-mediated
endocytosis. LDL binds to a specific LDL receptor
and is internalized in an endocytic vesicle.
 Receptors are recycled to the cell surface, while
cholesterol is further processed in the body.

7. FUNCTION OF LDL:
 The function of LDL is to deliver cholesterol to cells,
where it is used in membranes, or for the synthesis
of steroid hormones .

8. HIGH DENSITY LIPO-PROTEINS:
 Additionally, excess cholesterol from cells is
brought back to the liver by HDL in a process
known as reverse cholesterol transport .
 HDL is synthesized and secreted by the liver and
small intestine.
 It travels in the circulation where it gathers
cholesterol to form mature HDL, which then returns
the cholesterol to the liver via various pathways.

9. CONTINUE…..