Fig. 5. Cooperation of SipA and SipC in F-actin bundling. (A) Light scattering (U, intensity at 520 nm) over 1200 s using a range of concentrations of SipA (0.25–2.5 µM) incubated with a fixed concentration of SipC and F-actin (each 2.5 µM). Control traces with SipA alone (SipA, 2.5 µM), SipC and F-actin (both 2.5 µM), and SipA and F-actin (both 2.5 µM) are shown for comparison. Inset shows a transmission electron micrograph of F-actin (2.5 µM), incubated with SipA (2.5 µM) and SipC (0.25 µM). (B) Light scattering as in (A) using a range of concentrations of SipC (0.25–2.5 µM) incubated with a fixed concentration of SipA and F-actin (each 2.5 µM). Control traces with SipC alone (2.5 µM) and SipC and F-actin (both 2.5 µM) are also shown. Inset shows a transmission electron micrograph of F-actin (2.5 µM), incubated with SipA (0.25 µM) and SipC (0.25 µM).