of neutral phospholipid and acidic phospholipid [37]. Inverted micelle was observed
in focal fusion point of calcium ion-induced membrane fusion in lipid membrane
system including acidic phospholipid [38], and indeed membrane fusion was
induced by transition from lamellar phase to hexagonal II phase in membrane system
Fig. 6.5 Calcium ionophore function of phosphatidic acid (PA) molecules
(1) Calcium ions bind PA electrostatically. (2) PA is phase separated by replacement of hydration
water molecules by calcium ions and the phase separated region becomes hydrophobic
(3) Head of Ca-PA complex is hydrophobic and penetrates hydrophobic center of the membrane
(4) Inverted micelle structure is formed centering calcium ion
Fig. 6.6 Non-bilayer structures observed by freeze-fractured electron microscope
Hexagonal II structure of phosphatidylethanolamine is observed as parallel lines
Cardiolipn-Ca2 + complex is observed as arranged lipidic particles
6.5 Non-bilayer Forming Lipids and Function of Biomembrane
89
in focal fusion point of calcium ion-induced membrane fusion in lipid membrane
system including acidic phospholipid [38], and indeed membrane fusion was
induced by transition from lamellar phase to hexagonal II phase in membrane system
Fig. 6.5 Calcium ionophore function of phosphatidic acid (PA) molecules
(1) Calcium ions bind PA electrostatically. (2) PA is phase separated by replacement of hydration
water molecules by calcium ions and the phase separated region becomes hydrophobic
(3) Head of Ca-PA complex is hydrophobic and penetrates hydrophobic center of the membrane
(4) Inverted micelle structure is formed centering calcium ion
Fig. 6.6 Non-bilayer structures observed by freeze-fractured electron microscope
Hexagonal II structure of phosphatidylethanolamine is observed as parallel lines
Cardiolipn-Ca2 + complex is observed as arranged lipidic particles
6.5 Non-bilayer Forming Lipids and Function of Biomembrane
89