Fig. 8
A molecular model of the αcat-ABD homodimer facilitating actin bundling. The αcat-ABD/F-actin complex model based on the vin-ABD/F-actin cryo-EM structure suggests that two αcat-ABD molecules discretely bound to different actin filaments (e.g., αcat-ABD binds to F-actin through the α5-helix) can homodimerize through the crystallographically-identified ABD-dimer interface without causing any steric clash with actin filaments. We propose that the ABD-dependent dimerization of α-catenin facilitates actin bundling in an anti-parallel manner (‘+’ and ‘-’ indicate the barbed and pointed ends, respectively). The tight spacing of actin filaments (7~8 nm) in our atomic model is consistent with the inter-filament distances observed within the actin rods formed by ABD*-expressing cells (Supplementary Fig. 2c)
