Lipoprotein metabolism Essay Example | Topics and Well Written Essays - 500 words

Lipoprotein metabolism - Essay ExampleThis part accounts for the largest part of the cholesterol that is quantified as HDL-C in clinical laboratory. -HDLcan be fractionated make headway by density into HDL3 and HDL2, by apolipoprotein composition and size. About 5-15% of apo A-1 in the human plasma is linked to pre-electrophoretic mobility particles. This is further differentiated into pre3-LpA-I, 1-LpA-I and pre2-LpA-I particles. These particles where reverse cholesterol transport occurs. This occurs in extravascular compartments. It is not clear where the HDL particles and pre-electrophoretic mobility originates from. There are several mechanisms that have been proposed including cholesteryl ester transfer protein (CETP), direct interaction between cellphone membrane and free apolipoproteins, hepatic lipase (HL), release during the HDL interconversion by phospholipid transfer protein (PLTP) and direct secretion from enterocytes into plasma.High-density lipoprotein is produced in the intestine and liver. It plays a key out role in the reverse cholesterol transport. By accepting free cholesterol from the peripheral tissues, HDL lowers the blood cholesterol levels. HDL exchanges lipids and proteins with other lipoproteins. It donates apoproteins E and C11 to nascent VLDLs. HDL also produces a paraoxonase enzyme. This enzyme inhibits the oxidation of low-density lipoprotein. The HDL precursor particles can also absorb free cholesterol from the cell membrane in a process mediated by apoA-1, ApoA-IV and ATP binding cassette transporter 1. ApoA-1 is the HDLs major apolipoprotein. It activates the cholesterol acyltransferase (LCAT) (a lecithin enzyme) that esterifies the free original cholesterol to increase the efficiency of cholesterol packaging for transport. By acquisition of additional esters, triglycerides, and apolipoproteins, the particles of HDL3 are transformed into HDL2 particles which are relatively larger.By estension, HDL plays a role in transferri ng the