Fig. 1: Phalloidin bridges and flattens both terminal actin subunits at the pointed end. | Nature Communications

Fig. 1: Phalloidin bridges and flattens both terminal actin subunits at the pointed end.

From: Phalloidin and DNase I-bound F-actin pointed end structures reveal principles of filament stabilization and disassembly

Fig. 1

a Exemplary 2D classes of the undecorated pointed end of actin filaments. Box size: 324 × 324 Å. b Cryo-EM density map of the undecorated pointed end of F-actin at a resolution of 3.1 Å. Actin subunits are labeled depending on their location on the filament, so that the ultimate subunit is P0 and subunits towards the filament center have an increasing number (P1, P2, P3). The ultimate (P0) and penultimate (P1) actin subunits are colored in purple and lilac, respectively, while the subunits towards the filament center (P2 and beyond) are colored in light grey. The bound nucleotide is highlighted in yellow. c Cryo-EM density map of the phalloidin-bound pointed end of F-actin at a resolution of 3.7 Å. Phalloidin-bound actin subunits are colored from dark orange at the pointed end to lighter orange towards the filament center. The bound nucleotide and phalloidin are colored yellow and cyan, respectively. d Superimposition of the last four subunits (P0-P3) of the undecorated pointed end (purple and light grey) and the phalloidin-bound pointed end (shades of orange). The four actin subdomains (SD1-4), nucleotide binding site and hydrophobic cleft are annotated. The black arrow highlights the ~12° rotation of the outer subdomains (SD1, SD2) relative to the inner subdomains (SD3, SD4).

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