Lipoproteins

A lipoprotein is a biochemical assembly whose purpose is to transport hydrophobic lipid (a.k.a. fat) molecules in water, as in blood or ECF. They have a single-layer phospholipid and cholesterol outer shell, with the hydrophilic portions oriented outward toward the surrounding water and lipophilic portions of each molecule oriented inwards toward the lipids molecules within the particles. Apolipoproteins are embedded in the membrane, both stabilising the complex and giving it functional identity determining its fate. Thus the complex serves to emulsify the fats. Many enzymes, transporters, structural proteins, antigens, adhesins, and toxins are lipoproteins. Examples include the plasma lipoprotein particles classified under HDL, LDL, IDL, VLDL and ULDL (commonly called chylomicron) lipoproteins, which enable fats to be carried in all extracellular water including the blood stream (an example of emulsification), subgroups of which are primary drivers/modulators of atherosclerosis, the transmembrane proteins of the and the chloroplast, and bacterial lipoproteins.

...
Wikipedia