Ca2+-cardiolipin interaction in a model system. Selectivity and apparent high affinity.
The interaction of cardiolipin with Ca2+ was assessed by measuring the cardiolipin-mediated extraction of 45Ca2+ from an aqueous to an organic (methylene chloride) phase. Cardiolipin binds Ca2+ with high affinity [Kd(apparent) = 0.70 +/- 0.17 microM (S.D.)]. Cation-cardiolipin interactions are selective. Interaction of cardiolipin with Ca2+ is insensitive to Na+, but is inhibited by divalent cations with Mn2+ greater than Zn2+ greater than Mg2+. In addition La3+ and Ruthenium red are particularly potent inhibitors of Ca2+ binding by cardiolipin. Cardiolipin-mediated extraction of Ca2+ into an aqueous phase is also inhibited by phosphatidylcholine. Inhibition of Ca2+-cardiolipin interaction by phosphatidylcholine (a phospholipid known to stabilize the bilayer conformation) may implicate inverted, non-bilayer lipid structures in the binding.
D002118:Calcium / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002308:Cardiolipins / Q000378:metabolism*; D002413:Cations, Divalent; D007700:Kinetics; D007811:Lanthanum; D008954:Models, Biological; D012430:Ruthenium Red
D002250:Carbon Radioisotopes; D002308:Cardiolipins; D002413:Cations, Divalent; D012430:Ruthenium Red; D007811:Lanthanum; D002118:Calcium