Ca2+ is known to play a central role in triggering the fusion of lipid membranes, but the precise mechanism remains elusive. Molecular dynamics simulations performed on stacked bilayers show that Ca2+ has the unique ability to bridge the head groups of apposed phospholipids. The formation of this "anhydrous-complex" brings the bilayers into close contact, displacing water from the phospholipid head groups, and creates regions of local dehydration, which may act to nucleate the fusion process. This work is featured in the October 21, 2010 issue of the Journal of Physical Chemistry B.
