Question

What do proteins do in a cell membrane?

Answer 1

Hint: Membrane proteins are abundantly present and are the proteins that serve the purpose of contact with cell membranes. There are several categories of membrane proteins. These membrane protein categories are based on the location of the membrane protein.

Complete answer:
Membrane proteins perform several functions in the human body. They are as follows:
- Receptor proteins transfer signals between the external and internal environments of the cell.
- Transport proteins facilitate the movement of ions and molecules through the cell membrane.
- Membrane enzymes include many enzymes with several features like hydrolases, transferases and oxidoreductases.
- Cells identify each other and interact with each other with the help of cell adhesion molecules.
Integral membrane proteins are membrane proteins that are permanently adhered to the cell membrane. Integral membrane proteins can only be separated from the cell membrane with the use of some denaturing agents, detergents and nonpolar solvents.
Integral membrane proteins are divided into three classes on the basis of their relationship with the lipid bilayer. These classes are:
- Polytopic proteins
- Bitopic proteins
- Monotopic proteins
Peripheral membrane proteins are temporarily adhered to either the lipid bilayer or the integral proteins. They are attached with the help of non-covalent interactions. Peripheral membrane proteins dissolve with the help of polar reagents.

Note:
Membrane proteins that are a permanent part of the cell membrane and can penetrate the cell membrane are called integral membrane proteins. Membrane proteins that have a loose association with the cell membrane are called peripheral membrane proteins. Membrane proteins comprise almost one-third of all human proteins. Over half of the drugs acting on humans target membrane proteins.