ON PERIODIC CURVATURE AND STANDING-WAVE MOTIONS IN CELL-MEMBRANES

Cell membranes can form cubic arrangements and there is evidence for t he occurrence of periodic curvature in simple membranes. The periodici ty of the bilayer implies a standing wave character of vibrational mot ions. It is proposed that the periodic curvature reflects a dominating mode of standing wave oscillations, with the different cubic bilayer structures representing alternative standing wave conformations of the bilayer. The wave motions in lamellar liquid-crystalline phases, as w ell as in vesicles and membranes, which lack lateral periodicity, are known to exhibit statistically distributed undulations. The standing w ave character of conformational fluctuations of periodically curved me mbranes, on the other hand, results in an organisation in time and spa ce. Calculated models of standing wave conformations of membranes are demonstrated, and functional aspects of such biomembranes are discusse d. (C) 1997 Elsevier Science Ireland Ltd.