Question

What are lipoproteins? Describe their structural features and explain how different classes of lipoproteins are transported in the body.

Answer 1

Solution

• The Lipoproteins are macromolecular complexes of lipids and proteins that originate mainly from the liver and intestine and are involved in the transport and redistribution of lipids in the body.
• The lipoproteins are biochemical assembly whose primary purpose is to transport hydrophobic lipid (also known as fat) molecules in water, as in blood plasma or other extracellular fluids.
• They have a central hydrophobic core of non-polar lipids, primarily cholesterol esters and triglycerides.
• But This hydrophobic core is surrounded by a hydrophilic membrane consisting of phospholipids, free cholesterol, and apolipoproteins .

According to density of lipoproteins, classified as

• very low-density lipoproteins (VLDL),
• intermediate density lipoproteins (IDL),
• low-density lipoproteins (LDL),
• high-density lipoproteins (HDL)

lipoproteins are move from the intestines as chylomicrons—and from the liver as very low density lipoproteins (VLDL)—to most tissues for oxidation and to adipose tissue for storage.

The Reverse cholesterol transport (RCT) is a process by which cholesterol in nonhepatic tissues is transported back to the liver via plasma components- HDL(high density lipids), along with ATP binding cassette transporters.

The Low Density Lipids receptors are inserted into the plasma membrane and diffuse freely until they associate with clathrin-coated pits.

When Low density lipids receptors bind LDL particles in the bloodstream, the clathrin-coated pits are endocytosed into the cell.