Fig. 1: Structure, supramolecular assembly, and proposed membrane-repair mechanisms of A5.
From: Annexin-V stabilizes membrane defects by inducing lipid phase transition
a Bottom view (left) and side view (right) of A5 structure (PDB: 1A8A) with bound Ca2+ (yellow spheres). The membrane-facing side of the protein is slightly convex (right). b Top-view of A5 trimer, one monomer is colored as in a. c High-resolution HS-AFM image of A5 lattice on a PS-rich membrane. The lattice consists of hexamers-of-trimers (p6-trimers) forming a honeycomb pattern; in the center of each honeycomb resides an A5 trimer that displays rotational freedom (non-p6-trimer). The unit cell (a = b = 17.7 nm, γ = 60°; white dashed rhomboid) houses 2 p6-trimers and 1 non-p6-trimer. d, e Proposed membrane-repair mechanisms: patch resealing (d) suggests that the formation of A5 2D-lattices, triggered by the Ca2+ influx, stabilizes the membrane near lesions, followed by membrane resealing through fusion of intracellular vesicles. Annexin-mediated resealing (e) proposes that A5 assemblies along the edge of lesions provides local surface tension leading to membrane fusion.
