Apolipoproteins are proteins that bind to lipids (fats) to form lipoproteins, which transport fats through the bloodstream. They play a crucial role in lipid metabolism and help regulate cholesterol levels in the body. Different types of apolipoproteins, such as Apolipoprotein A and Apolipoprotein B, have specific functions and are associated with various health conditions. These proteins serve as structural components of lipoproteins and act as ligands for receptors, facilitating the uptake of lipids by cells. Abnormal levels of apolipoproteins can indicate an increased risk of cardiovascular diseases, making them important markers in medical assessments.