Cover picture: A group IIA secretory PLA2 (green ribbon) bound to the surface of a phospholipid membrane. A phospholipid molecule is shown bound to the catalytic site of PLA2. Lys10 and Lys82 (blue) are involved in ionic interactions with membrane lipids, while Lys7 is shown hydrogen-bonded to the carbonyl oxygen of the lipid. The side chains of Phe3 and Ile63 (yellow) make hydrophobic contacts with the membrane. A nucleophilic water molecule is shown as a turquoise sphere between His48 and the sn-2 ester bond of the phospholipid substrate. A Ca²⁺ cofactor (magenta sphere) is between the carboxyl group of Asp49 and the phosphate group of the substrate, which serve as Ca²⁺ ligands. The structures of PLA2 and of the lipid are taken from Han et al., 1997. J. Biol. Chem. 272:3573 and Pascher et al., 1987. Biochim. Biophys. Acta 896:77. See the article by Tatulian on p. 789.