Lipids are not soluble in water, so they are transported in the blood in combination with proteins. Lipoproteins are any compound or complex containing lipid and protein. Fatty acids released from adipose tissue bind to the plasma protein albumin and are transported to other tissues as lipoproteins. More complex assemblies of lipids and proteins consist of phospholipids and proteins surrounding lipids. The phospholipids and proteins have charged groups facing outward, which attracts water and makes the lipoprotein soluble in water. The internally located lipids are separated from the water by the phospholipids and proteins.