[Music] lipoproteins let's take a look at the introduction lipoproteins are a group of proteins synthesized in the small intestine and liver that transport hydrophobic lipids such as cholesterol triglycerides and phospholipids throughout the body types are named based on the density of their contents and include chylomicron chylomicron remnants a lipoprotein or VLDL the LDL remnant or IDL which is intermediate density lipoprotein LDL which is low-density lipoprotein and HDL which is high density lipoprotein an important point to note here is that chylomicrons are the least dense and HDL are the most dense lipids present in lipoproteins triglycerides phospholipids free cholesterol which is uh nasteria fied cholesterol ester structure the structure consists of a hydrophobic core and a hydrophilic shell of bearing lipids the core which is hydrophobic lipids are made up of cholesterol esters and triglycerides the shell which is hydrophilic lipid components consists of free cholesterol phospholipids and hydrophilic proteins so called a palapa proteins basics of lipid transport lipids are nonpolar substances and the transport medium in our body is blood which is polar lipids are insoluble in a polar medium so they cannot be transported directly or alone so for transportation of lipids in the body they need a vehicle to overcome this problem lipoproteins play a crucial role in transportation of lipids by making them polar with a lipid and protein combination the lipid portion which is nonpolar is placed in the core and the protein portion which is polar is placed in the periphery so that lipoprotein can easily travel in the blood and helps in the transportation of lipids from one place to another chylomicrons a lipoprotein that carries lipids and cholesterol from the small intestine to adipocytes cardiac muscle and skeletal muscle it is composed of an outer phospholipid with embedded Apryl lipoproteins and a core containing lipids and cholesterol chylomicrons are very large particles it is mainly composed of triglycerides more than cholesterol chylomicrons contain dite derived triacylglycerol chylomicrons are secreted by the intestinal epithelial cells into lymphatic functions transport of dietary triglycerides from the intestine to the peripheral tissues chylomicron remnants are chylomicrons that are depleted of triglycerides transport of cholesterol to the liver in the form of chylomicron remnants apel lipo proteins associated with chylomicrons are a po e apis c2 which activates capillary lipoprotein lipase and Apryl b48 very low density lipoprotein B LDL VLDL is a lipoprotein secreted by the liver it comprises of triglycerides more than cholesterol its function is that it transports triglycerides from the liver to the peripheral tissues it is converted to LDL by hydrolysis of fatty acids by capillary lipoprotein lipase aple lipo proteins associated with VLDL are April II say two and B hundred intermediary density lipoprotein or IDL its composition is cholesterol and triglycerides degradation of VLDL forms IDL it transports triglycerides and cholesterol to the liver from the peripheral tissues Apel lipoproteins associated are April E and B hundred low-density lipoprotein LDL it is composed more of cholesterol than triglycerides LDL is formed from IDL secondary to hepatic lipase with modification and peripheral tissue and the liver it is endocytosed by target cells with LDL receptors and D graded releasing cholesterol which decreases further uptake of cholesterol it transports cholesterol from the liver to peripheral tissues it is commonly referred to as bad cholesterol a palapa proteins associated are april-b hundred high density lipoprotein HDL it is mainly composed of cholesterol more than triglycerides it is secreted by intestinal epithelium and liver it transports cholesterol from peripheral tissues example admiral sclerotic arteries to the liver by reverse cholesterol transport where it is excreted example via bile hence called as good cholesterol the higher the concentration the lower the risk for coronary artery disease a palapa proteins associated are April II a 1 and C 2 April a one component of HDL activates l cat to form cholesterol esters transfers a possi to and April II to nascent chylomicrons and the LDL april lipoproteins proteins present in lipoproteins are known as April lipoproteins their synthesis occurs in the rough endoplasmic reticulum and ecology they are April a 1 a 2 B 48 B hundred c1 c2 c3 and E functions of April lipoproteins a1 it activates lecithin cholesterol acyl transferase which is elk at that esterified tissue cholesterol picked up by HDL it is a major structural protein for HDL April lipoprotein c2 it activates capillary lipoprotein lipase which releases fatty acids and glycerol from chylomicrons the LDL and IDL April lipoprotein B 48 is a component of chylomicrons B hundred contains the b48 domain plus the LDL receptor recognition domain permitting binding to LDL receptors it's the only structural protein in LDL April lipoprotein II mediates uptake of chylomicron remnants and intermediate density lipoproteins by the liver density of lipoproteins density is directly proportional to the percentage of proteins density is inversely proportional to TG content and sighs so chylomicron has the least density and largest size maximum TG content and minimum proteins HDL has maximum density so is smallest in size has minimum TG and maximum proteins based on electro phoretic separation from cathode to anode the order of lipoprotein in an electrophoretogram is as follows chylomicron LDL which are beta lipoprotein VLDL which are pre beta lipoproteins IDL or broad beta lipoprotein and HDL alpha lipoprotein