Which type of proteins are bound to the surface of the cell membrane?

Peripheral proteins are those that are bound to the surface of the cell membrane rather than being embedded within the membrane structure. They typically associate with the outer or inner surfaces of the membrane and can be attached to integral proteins or to the lipid bilayer itself through non-covalent interactions. These proteins play vital roles in various cellular functions, including signaling, maintaining the cell's shape, and facilitating communication with the environment.

In contrast, integral proteins extend across the membrane and may span from one side to the other, playing crucial roles in transport and communication. Carrier proteins and channel proteins, both types of integral proteins, are specifically involved in moving substances across the membrane, either by changing shape (carrier proteins) or forming openings (channel proteins) for ions and molecules to pass through. While all these proteins are important for cell function, it is the peripheral proteins that are specifically associated with the surface of the membrane, distinguishing them in function and positioning.