Phospholipids are the important constituent of the cell that provides structure as well as protection to the cell. The first identified phospholipids was lecithin from the egg yolk. It has hydrophilic head and a hydrophobic tail, that arranges in the form of bilayer so as to assist the cell in exchange of important nutrients. They are made up of fatty acid, alcohol, phosphate and the platform that helps in the attachment of fatty acid. These way phospholipids help the cell membrane in several ways. Beside this, it is also used for several purposes like it is used for designing different types of useful drugs, it is also a signaling molecule for human body, major source for energy storage and a structure component of the cell. These are some of the very important function of phospholipids.
Phospholipids are made of different classes of molecules and this in turn depends upon the elements that are attached to the head of phospholipids. Therefore, on this basis phospholipids are classified into different groups:
1. Phophatidylcholine: It is one of the most abundant phospholipids present in the cell membrane that accounts for 50%. This molecule is rich in choline and hence choline is the central element here. But choline itself is not synthesized by the cell. For this, the dietary source is utilized and choline is synthesized. This choline when taken up by the cell is quickly phosphorylated by choline kinase and hence phosphocholine is formed. Then the product obtained reacts with cytidine triphosphate forming cytidine diphosphocholine. Then in the endoplasmic reticulum is CDP- choline, that catalyses reaction of cytidine diphosphocholine with sn- 1,2 diacylglycerols forming phosphatidylcholine. The reaction here is though explained in some simple steps but the complete process is much more elaborated. The process may be length but the end product is useful for the cell membrane and also is important for proper functioning of brain and liver.
2. Phosphatidylethanolamine: This is the other main lipid in animal and plant that is a foundation for phospholipids bilayer. These phospholipids are the main component of the microbial membrane. They are generally found in the inner part of the cell membrane and are generally found in nervous tissue. It helps in fusion of membrane and regulates membrane curvature and also increases viscosity of the membrane. This way, phosphatidylethanolamine serve cell membrane in different ways.
3. Phosphatidylinositol: It is the other main constituent of the membrane that helps in metabolic process in almost all the living beings. It is mostly present in brain tissue. It is found in the inner side of the cell membrane and in very less amount in comparison to the others. They are the main source of diacylglycerol that acts as the messenger for the cell. Phosphatidylinositol is main source of arachnoids acid that helps in biosynthesis of eicosanoids.
4. Phosphatidylserine: It is one of the important members of phospholipids that are also present in cell membrane. Beside the function in cell membrane it also helps to decline the bad functioning of the brain and any kind of depression in the elderly people. They are involved in cell signaling and many more of the activity that takes place in the body.
These are some of the important types of phospholipids that are present in cell membrane and helps in its proper functioning. All this phospholipids have same function but they are named differently because of their structure and some differences in the chemical property. Phospholipids are important for living being that serve in different ways for proper functioning of the body.