The plasma membrane is the biological membrane found in all living cells. The plasma membrane is composed of the lipid bilayer and the protein molecules. Some protein molecules of plasma membranes are of globular shaped, and these are inserted into the lipid bilayer. Few proteins are found in the peripheral region. Membrane proteins are embedded in the cell membrane. These are the channel protein, carrier protein and the receptor protein. These proteins help in transporting different substances inside the cell.
Channel Protein and Carrier Protein Regulate the Cell Homeostasis
Channel proteins are also called integral protein, that mainly functions in the transportation of molecules across the membranes by developing the channel. Some of the channels are selectively made; they allow some of the ions to move into the cell. These channel proteins may pass the cations but not the anions. Both ions possess different permeability. The hydrophilic core of the protein helps in hydrated opening. Aquaporins are the examples of channel proteins which assist in the transportation of water molecules across the membrane at a rapid rate. Channel proteins are gated that allow closing and opening of the gates based upon the signals.
Carrier proteins are the other group of the specific protein that helps in the facilitated diffusion across the cell membranes. These specific proteins bind with the molecule, and conformational changes occur in the molecule. The binding site of the carrier protein is very selective; they can distinguish between the d and I- sugars. Carrier proteins are used in the active transportation of molecules. Receptor proteins are found in the cell membrane that helps in receiving the signals (chemical signals). Few examples of receptor proteins are G-proteins and the hormone receptors. These receptor proteins have a certain shape that enables some molecules to bind with them. The binding of the molecule changes the shape of the protein to produce some response in the cell. Glycoproteins are the receptor protein in which carbohydrates are attached. Cholesterol molecules are also attached with the cell membranes, and these works to prevent the phospholipid molecules from sticking to one another; this enables the fluidity of the membrane.
Cellular Communication
Cellular communication is basically the intercellular communication. Different cells communicate with each other by sending some chemical signal, and they are used to maintain the homeostasis. Long- ranges chemical signals are secreted directly into the blood so that it can be transported anywhere in the body.
