Fig. 1. Cryo-EM structures of the WRC in different Rac1-bound states.
a–c Schematic and cryo-EM density of the indicated WRCs. Black dotted lines indicated by arrowheads are flexible peptide linkers tethering Rac1 to the WRC. The meander sequence is traced by white dotted lines. Other dotted lines and cylinders in the WRCAD-Rac1 structure refer to sequences of which the densities are not observed in WRCAD-Rac1, but present in WRCapo and WRCD-Rac1. Red dots indicate locations to which Rac1 is tethered. d–f Pyrene-actin polymerization assays measuring activities of the indicated WRCs used in cryo-EM. Reactions use the NMEH20GD buffer (see Methods) and contain 3.5 µM actin (5% pyrene-labeled), 10 nM Arp2/3 complex, 100 nM WRC230WCA or WAVE1 WCA, and/or 6 µM Rac1QP. A. U. for arbitrary units. Results are representative of at least two independent repeats. Source data for d–f are provided as a Source Data file.