91Ó°ÊÓ

Answer: The three main types of membrane proteins are integral, peripheral, and lipid-anchored proteins. Integral membrane proteins are embedded within the lipid bilayer and facilitate the movement of molecules across the membrane through receptors, channels, or transporters. Peripheral membrane proteins do not penetrate the hydrophobic core of the membrane but associate with the polar head groups or with integral membrane proteins, functioning in cell signaling, anchoring intracellular components, and acting as enzymes. Lipid-anchored membrane proteins are covalently attached to lipid molecules within the lipid bilayer, and are involved in cell signaling, enzyme activity, and molecular recognition.