Surface topography of the p3 and p6 annexin V crystal forms determined by atomic force microscopy

Annexin V is a member of a family of structurally homologous proteins shari ng the ability to bind to negatively charged phospholipid membranes in a Ca 2+-dependent manner. The structure of the soluble form of annexin. V has be en solved by X-ray crystallography, while electron crystallography of two-d imensional (2D) crystals has been used to reveal the structure of its membr ane-bound form. Two 2D crystal forms of annexin V have been reported to dat e, with either p6 or p3 symmetry. Atomic force microscopy has previously be en used to investigate the growth and the topography of the p6 crystal form on. supported phospholipid bilayers (Reviakine et al., 1998). The surface structure of the second crystal form, p3, is presented in this study, along with an improved topographic map of the p6 crystal form. The observed topo graphy is correlated with the structure determined by X-ray crystallography . (C) 2000 Academic Press.