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Publication Abstract from PubMed

Annexins are a family of calcium- and phospholipid-binding proteins implicated in a number of biological processes including membrane fusion and ion channel formation. The crystal structure of the annexin XII hexamer, refined at 2.8 A resolution, forms a concave disk with 3-2 symmetry, about 100 A in diameter and 70 A thick with a central hydrophilic pore. Six intermolecular Ca2+ ions are involved in hexamer formation. An additional 18 Ca2+ ions are located on the perimeter of the disk, accessible only from the side of the hexameric disk. On the basis of the hexamer structure we propose here a new mode of protein-phospholipid bilayer interaction that is distinct from the hydrophobic insertion of typical membrane proteins. This speculative model postulates the Ca(2+)-dependent insertion of the hydrophilic annexin XII hexamer into phospholipid bilayers with local reorientation of the bilayer phospholipids.

Crystal structure of the annexin XII hexamer and implications for bilayer insertion.,Luecke H, Chang BT, Mailliard WS, Schlaepfer DD, Haigler HT Nature. 1995 Nov 30;378(6556):512-5. PMID:7477411^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.