The crystal structure of annexin VI indicates relative rotation of the two lobes upon membrane binding

AbstractThe crystal structure of bovine liver annexin VI has been determined to low resolution by molecular replacement. The first lobe (domains 1–4) is rotated about 90° relative to the second lobe (domains 5–8). Since the same crystal form (P43, 68 × 68 × 205 Å) grew from (NH4)2SO4, polyethylene glycol, and sodium acetate with and without added calcium, this probably reflects the structure in solution. When bound to a lipid monolayer both lobes of annexin VI are coplanar. This implies a significant change in conformation upon binding to membranes