produced synthetically. Each source has a unique profile of individual phospholipid species, as well as fatty acids, and consequently differing applications in food, nutrition, pharmaceuticals, cosmetics and drug delivery. In signal transduction Some types of phospholipid can be split to produce products that function as second messengers in signal transduction. Examples include phosphatidylinositol (4,5)-bisphosphate (PIP2), that can be split by the enzyme phospholipase C into inositol triphosphate (IP3) and diacylglycerol (DAG), which both carry out the functions of the Gq type of G protein in response to various stimuli and intervene in various processes from long term depression in neurons to leukocyte signal pathways started by chemokine receptors. Phospholipids also intervene in prostaglandin signal pathways as the raw material used by lipase enzymes to produce the prostaglandin precursors. In plants they serve as the raw material to produce jasmonic acid, a plant hormone similar in structure to prostaglandins that mediates defensive responses against pathogens. Food technology Phospholipids can act as emulsifiers, enabling oils to form a colloid with water. Phospholipids are one of the components of lecithin, which is found in egg yolks, as well as being extracted from soybeans, and is used as a food additive in many products and can be purchased as a dietary supplement. Lysolecithins are typically used for water–oil emulsions like margarine, due to their higher HLB ratio. Phospholipid derivatives See table below for an extensive list. Natural phospholipid derivates: egg PC (Egg lecithin), egg PG, soy PC, hydrogenated soy PC, sphingomyelin as natural phospholipids. Synthetic phospholipid derivates: Phosphatidic acid (DMPA, DPPA, DSPA) Phosphatidylcholine (DDPC, DLPC, DMPC, DPPC, DSPC, DOPC, POPC, DEPC) Phosphatidylglycerol (DMPG, DPPG, DSPG, POPG) Phosphatidylethanolamine (DMPE, DPPE, DSPE DOPE) Phosphatidylserine (DOPS) PEG phospholipid (mPEG-phospholipid, polyglycerin-phospholipid, functionalized-phospholipid, terminal activated-phospholipid) Abbreviations used and chemical information of glycerophospholipids See also Cable theory Galactolipid Sulfolipid References Anionic surfactants