Common domain structure of Ca2+ and lipid-binding proteins.

The phospholipase A2 inhibitor, lipocortin, shares common sequences with three abundant Ca2+-regulated membrane binding proteins of unknown function which are present in many cell and tissue types. A two-domain model for the structure of lipocortin is described and it is suggested that the new Ca2+-regulated proteins each contain at least one lipocortin domain. The structural and biochemical properties of each protein indicate that they all directly interact with phospholipids. Potential sites of interaction with the lipocortin domain are identified on the basis of homology with phospholipid transfer proteins and phospholipase A2.