Fig. 3

Comparison of modelled actin polymerisation curves to experimental data. (a) Cross-filament model (red) in comparison to experimental actin polymerisation rate (black dashed, close to the baseline), using 300 nM Las17 and 5 µM actin. (b) Cross-filament model (red) compared to experimental data (black dashed) for the cross-filament nucleator Cobl²⁸ with 40 nM Las17 and 2 µM actin. (c) Experimental actin only control (gray) and nucleated by Las17 (magenta), for 300 nM Las17 and 5 µM actin, compared to: control actin-only model (black); cross-filament model (blue); longitudinal model (red); and longitudinal model with Las17 dimerization (orange). The experimental rates have been adjusted for the change in buffer from 1xKME to 0.5xKME, as discussed in Supplementary Material. (d) Longitudinal model (blue) compared to experimental data for Spire (black dashed), with 500 nM Las17 and 4 µM actin²⁷. (e) Sensitivity analysis showing the effect of Sla1 concentration and SH3 cloud concentration on nucleation rate. Rate decreases of > 10% are in increasingly darker shades of orange.