noun. Any of various proteins that combine with a lipid to form a lipoprotein and are a constituent of chylomicrons, HDL, LDL, and VLDL.

noun. Any protein that can bind with a lipid to form a lipoprotein

"Most of his argument is based on a recent study that showed progresson of artherosclerotic plaques with a low-carb diet in apolipoprotein E-deficient mice, a model commonly used to study arteriosclerosis."