Clearly, membrane proteins themselves have domains that keep membranes in or attached to the membrane, provide catalytic surfaces and allow interactions inside, across and outside of cells and organelles. Membranes anchor proteins in several ways. As noted, membrane proteins, like phospholipids, are amphipathic, with hydrophobic domains that non-covalently interact strongly with the fatty acid interior of membranes. Some integral membrane proteins span the entire membrane, with hydrophilic domains facing the cytosol or cell exterior. Peripheral proteins bind to a membrane surface through non-covalent interactions. Examples of integral and peripheral membrane proteins, glycoproteins and lipoproteins are illustrated below.
286 Domains of Membrane Proteins