Phospholipids are commonly found in the phospholipid bilayer of membranes. These specific properties allow phospholipids to play an important role in the phospholipid bilayer. A mitochondrion contains outer and inner membranes composed of phospholipid bilayers and proteins. One way hemolysin lyses erythrocytes is by forming pores in phospholipid bilayers. The precursor to the remodeling pathway is a phospholipid, which is typically phosphatidylcholine (PC). Phospholipase A2 causes hemolysis by lysing the phospholipid cell membranes of red blood cells. Phosphatidylcholine is a major phospholipid in eukaryotic cell membranes. Where phosphatidylcholine is the principal phospholipid in animals, phosphatidylethanolamine is the principal one in bacteria. These enzymes are regulated by inositol and choline, both of which are phospholipid precursors. Rubber particles are surrounded by a single phospholipid membrane with hydrophobic tails pointed inward. Phospholipid vesicles have also been studied in biochemistry. This technique allows for large scale production of phospholipid liposomes and subsequent material nanoencapsulations. The main emulsifier in egg yolk is called lecithin, which is a phospholipid. Annexin A5 forms a shield around negatively charged phospholipid molecules. PA is a negatively charged phospholipid, whose small head group promotes membrane curvature.