Cell Membranes And Cellular Membranes

Cellular membranes are complex mixtures of proteins and lipids. Cell membranes are composed of a phospholipid bilayer, consists of two leaflets of phospholipid molecules whose fatty acyl tails form the hydrophobic interior of the bilayer; and proteins that span the bilayer and/or interact with the lipids on either side of the two leaflets. Transmembrane proteins are the type of membrane proteins which span the entire length of the cell membrane. They are embedded between the phospholipids and provides a channel through which molecules and ions can pass into the cell. They also enable communication between cells by interacting with chemical messengers. Membrane proteins were classified into two broad categories- integral and peripheral, based on the nature of the

The integral proteins contain residues with hydrophobic side chains that interact with fatty acyl groups of the membrane phospholipids, thus anchoring the protein to the membrane. These transmembrane proteins contain one or more membrane-spanning domains as well as domains extending into the aqueous medium on each side of the bilayer. Peripheral proteins, do not interact with the hydrophobic core of the phospholipid bilayer, they are primarily associated with the membrane by specific protein-protein interactions. , Schematic diagram of typical membrane proteins in a biological membrane

The lipid composition of the membrane is very complex; a typical membrane contains hundreds to thousands of chemically distinct species of lipid molecule, which acts as a solvent for membrane proteins. These lipid molecules generally interact non-specifically with the protein molecules, although a few ‘hot-spots’ may be present on the protein where anionic lipids bind with high affinity. There is a certainty that changing the chemical composition of the lipid bilayer surrounding an integral membrane