Structural Insights into the Regulation of Actin Capping Protein by Twinfilin C-terminal Tail

• Twinfilin binds CP via TWtail that has sequence similarity to CARMIL CPI. Here we present the crystal structure of in complex with TWtail. and CPI restrict distinct conformations. Unlike CPI, forms a stable ternary V-1. Our data suggest acts cooperatively V-1 destabilize F-actin. is conserved actin regulator interacts capping protein (CP) C terminus residues (TWtail) exhibits interaction (CPI) motif CARMIL. report CP. showed although bind an overlapping surface their middle regions, they exhibit different CP-binding modes at both termini. Consequently, conformations open closed forms, respectively. Interestingly, V-1, which targets away from binding site, also favors open-form Consistently, striking contrast rapidly dissociates results demonstrate unique regulates manner