They release arachidonic acid from membrane phospholipids. It synthesizes lipids, phospholipids, and steroids. The other half are lipids, namely phospholipids and cholesterol. Bile consists of water, electrolytes, bile acids, cholesterol, phospholipids and conjugated bilirubin. These three proteins are colocalized within spherical particles containing phospholipids and cholesterol. A cell membrane consists of proteins and phospholipids. Biological membranes typically include several types of molecules other than phospholipids. Other hemolysins lyse erythrocytes by hydrolyzing the phospholipids in the bilayer. DHA is a major fatty acid in brain phospholipids and the retina. The hydrophobic chains of sphingomyelin tend to be much more saturated than other phospholipids. Examples include cholesterol, phospholipids, and triglycerides. Thudichum discovered in human brain some phospholipids (cephalin), glycolipids (cerebroside) and sphingolipids (sphingomyelin). There are many other phospholipids, some of which are glycolipids. Vaccination was associated with significant reductions in total cholesterol, free cholesterol, phospholipids, and triglycerides. It is one of the few membrane phospholipids not synthesized from glycerol.