Lipoprotein, low density from human plasma

Lipoprotein, low density from human plasma has been used:

• as an additive in cholesterol-free RPMI media
• as a component in buffer to perform an assay for measuring lipid peroxidation
• to stimulate hepatic macrophages
• as a plasma protein to determine pazopanib unbound fraction (fu%) by equilibrium dialysis

LDL and HDL transport both dietary and endogenous cholesterol in the plasma. LDL is the main transporter of cholesterol and cholesteryl esters and makes up more than half of the total lipoprotein in plasma. LDL is absorbed by the liver and other tissues via receptor mediated endocytosis. The cytoplasmic domain of the LDL receptor facilitates the formation of coated pits; receptor-rich regions of the membrane. The ligand binding domain of the receptor recognizes apo-B100 on LDL, resulting in the formation of a clathrin-coated vesicle. ATP-dependent proton pumps lower the pH inside the vesicle resulting dissociation of LDL from its receptor. After loss of the clathrin coat the vesicles fuse with lysozomes, resulting in peptide and cholesteryl ester enzymatic hydrolysis. The LDL receptor can be recycled to the cell membrane. Insulin, tri-iodothyronine and dexamethasome have shown to be involved with the regulation of LDL receptor mediated uptake.

Freezing of lipoprotein solutions may cause structural or compositional changes.

Low density lipoproteins are smaller than VLDL and IDL (26 nm) (MW approximately 3.5 million) and more dense (~1.04). The protein component of LDL is apolipoprotein B100. LDL contains 20-22% protein, 10-15% triglycerides, 20-28% phospholipids, 37-48% cholesteryl esters and 8-10% cholesterol.

Solution in 150 mM NaCl and 0.01% EDTA, pH 7.4

View more information on lipoprotein function and lipid transport at www.sigma-aldrich.com/enzymeexplorer

RESEARCH USE ONLY. This product is regulated in France when intended to be used for scientific purposes, including for import and export activities (Article L 1211-1 paragraph 2 of the Public Health Code). The purchaser (i.e. enduser) is required to obtain an import authorization from the France Ministry of Research referred in the Article L1245-5-1 II. of Public Health Code. By ordering this product, you are confirming that you have obtained the proper import authorization.