MSH: Lipid-protein complexes involved in the transportation and metabolism of lipids in the body. They are spherical particles consisting of a hydrophobic core of TRIGLYCERIDES and CHOLESTEROL ESTERS surrounded by a layer of hydrophilic free CHOLESTEROL; PHOSPHOLIPIDS; and APOLIPOPROTEINS. Lipoproteins are classified by their varying buoyant density and sizes.,NCI: An important class of serum proteins in which a spherical hydrophobic core of triglycerides or cholesterol esters surrounded by an amphipathic monolayer of phospholipids, cholesterol and apolipoproteins. Classified according to density: chylomicrons, large low density particles, very low density, low density and high density species. Important in lipid transport, especially cholesterol transport in the blood stream. Abnormalities in lipoprotein metabolism have been implicated in certain heart diseases. (On-line Medical Dictionary)