Any of the macromolecular complexes that are the form in which lipids are transported in the blood. They consist of a core of hydrophobic lipids covered by a layer of phospholipids and apoproteins, which make the complex water-soluble. There are four main classes of lipoproteins: chylomicrons, in which lipids are transported after a meal from the intestine to tissues, where they are stored or used; very low density lipoproteins (VLDL); low density lipoproteins (LDL); and high density lipoproteins (HDL). VLDL and HDL are produced by both the liver and the intestine; LDL is produced by the metabolism of VLDL.
- α-l. — high density lipoproteins which migrate in the alpha position in paper chromatography. Inherited deficiency of these proteins is described in humans but there is no known animal model of the disease.
- l. factor Xa inhibitor — a blood coagulation inhibitor present in the low density lipoprotein fraction of plasma.
- high density l. (HDL) — a fraction of lipoproteins separable by ultracentrifugation.
- intermediate density l. (IDL) — intermediate in density between LDL and VLDL; migrate in electrophoresis with β-globulins.
- l. lipase — specific lipase hydrolyzing lipoproteins.
- l. lipase deficiency — see hyperlipoproteinemia.
