In contrast to monovalent ions like Na + , K + , and Cs + , the bivalent Mg 2+ and Ca 2+ (and the similarly high-chargedensity Li + ) ions removed EB from the membrane, indicating a potential role for the transition of EB into the intracellular medium. One factor contributing to this behaviour may be the adoption of the belted 1:1 EB:M z+ in complexes, which provide a small degree of charge screening.