The role of local design in membranes.

The IMP arrays are integral membrane multiprotein complexes that may be site-specific control centers regulating the local concentration of specific ions by functioning as pumps, gates, or channels. In the case of the fusion rosette, an increase in Ca2+ may trigger local membrane fusion; in other cases, Ca2+ or H+ may be important physiological regulators. Ca2+ dependent regulatory proteins, such as calmodulin, and other parameters prevent widespread dispersion of the ions and permit fine local regulation.