Ca²⁺ is essential for many physiological processes, such as membrane fusion, leading to the release of neurotransmitters, enzymes, or hormones. Experimental evidence suggests the bridging of opposing bilayers by Ca²⁺, and subsequent dehydration of the phospholipid head group, in the early stages of the membrane fusion process.

Our hypothesis, that Ca²⁺ plays a key role in the membrane fusion process, is corraborated with molecular dynamics simulations in the isobaric-isothermal ensemble. Simulations performed on a mixture of Ca²⁺, dimethylphosphate (DMP) and water show that Ca²⁺ bridging of phosphate head groups is indeed possible, and that upon briding, water is expelled from the phosphate head-group.