Figure 2.

The hydrophobic effect and a potentially similar mechanism for protein assembly within membranes. (A) Binding of two proteins (green and grey) in water. Shown in dark blue on the left is the shell of water molecules in contact with protein (the first solvation shell). Binding is accompanied by a significant reduction in the contact surface between protein and water molecules—the 'solvent-exposed surface area'. On the right side, the fine structure of water that surrounds the protein complex is illustrated. (B) Assembly of a membrane protein complex. The lipids in the first and second layers around the proteins are assumed to be entropically confined and are marked by black dots (76 when grey and green proteins are separated, and only 56 and 62 in the 'tight' or 'lipid-mediated' complexes).