Which term describes the two major classes of membrane proteins?

Which term describes the two major classes of membrane proteins?

• A. 2 types of protein in cell membrane
• B. Peripheral proteins
• C. Integral proteins
• D. Peripheral and integral

Answer: (D)

The two major classes of membrane proteins are peripheral proteins and integral proteins. Integral proteins are embedded in the lipid bilayer and often span it, with hydrophobic regions that interact with the lipid core. This makes them tightly associated with the membrane and usually requires detergents to solubilize. Peripheral proteins, on the other hand, sit on the membrane surface and attach by electrostatic interactions or by binding to integral proteins or lipids; they can be removed with milder treatments like high salt or pH changes. Knowing both categories helps explain how membranes carry out their functions: integral proteins include channels and transporters that cross the membrane, while peripheral proteins often play roles in signaling, cytoskeletal attachment, or enzymatic activity at the surface. The term that describes both is exactly peripheral and integral. The other options are incomplete or vague because they refer to only one class or a non-specific description of membrane proteins.

The two major classes of membrane proteins are peripheral proteins and integral proteins. Integral proteins are embedded in the lipid bilayer and often span it, with hydrophobic regions that interact with the lipid core. This makes them tightly associated with the membrane and usually requires detergents to solubilize. Peripheral proteins, on the other hand, sit on the membrane surface and attach by electrostatic interactions or by binding to integral proteins or lipids; they can be removed with milder treatments like high salt or pH changes. Knowing both categories helps explain how membranes carry out their functions: integral proteins include channels and transporters that cross the membrane, while peripheral proteins often play roles in signaling, cytoskeletal attachment, or enzymatic activity at the surface. The term that describes both is exactly peripheral and integral. The other options are incomplete or vague because they refer to only one class or a non-specific description of membrane proteins.