Low-density cholesterol lipoprotein. Illustration of the structure of a low-density lipoprotein (LDL) particle, a form of cholesterol found in the blood. Mainly composed of lipids, this complex structure includes carrier proteins (pink) known as apo-B proteins, which assist LDL transport in the blood. Also found in the outer coat are phospholipids (stalked spheres) & free cholesterol molecules (yellow). Within the core, cholesterol molecules (yellow) are bound into long esters by fatty acid chains (green). Research points to high blood levels of LDL particles leading to increased risk of narrowing of the arteries (atherosclerosis), coronary heart disease & stroke