RAT ANNEXIN-V CRYSTAL-STRUCTURE - CA2-INDUCED CONFORMATIONAL-CHANGES()

Annexins are a family of calcium- and phospholipid-binding proteins im plicated in mediating membrane-related processes such as secretion, si gnal transduction, and ion channel activity. The crystal structure of rat annexin V was solved to 1.9 angstrom resolution by multiple isomor phous replacement. Unlike previously solved annexin V structures, all four domains bound calcium in this structure. Calcium binding in the t hird domain induced a large relocation of the calcium-binding loop reg ions, exposing the single tryptophan residue to the solvent. These alt erations in annexin V suggest a role for domain 3 in calcium-triggered interaction with phospholipid membranes.