Fig. 2: EEA1 and Rab5 spontaneously drive collapse–extension cycles without the assistance of additional components.

a, EEA1 alone (blue) in the extended state undergoes an entropic collapse (red) on Rab5(GTP) addition followed by a recovery to the original extended state over time. A second round of Rab5(GTP) addition results in another EEA1 collapse–extension cycle. The filled coloured circles correspond to experimental data and the solid black lines are fit to equation (1). b,c, Collapse–extension cycles are quantified from changes over time in the local slope minima α_min (b) and persistence length λ (c). The quantified results in (b) and (c) show that EEA1 in the extended state (blue; α_min ≈ 3/4 and λ ≈ 170 nm) undergoes a collapse (red; α_min ≈ 2/3 and λ ≈ 70 nm) on binding to Rab5(GTP), and recovers over time to the original extended state (red; α_min ≈ 3/4 and λ ≈ 190 nm). A second collapse–extension cycle occurs on the re-addition of Rab5(GTP). The blue and red solid lines correspond to α_min = 3/4 (extended state) and α_min = 2/3 (collapsed state). Flexibility increase is only attributed to the binding of Rab5(GTP), as confirmed by the addition of Rab5(GDP) and GST, which do not interact with EEA1. d, Scaling exponent α(τ) of EEA1 alone (blue) in the extended state and on the sequential addition of 1, 2 and 10 μM of Rab5(GDP) (grey). The results from the addition of 2 μM GST (yellow) to EEA1 (right). e,f, The α_min (e) and persistence length λ (f) values, quantified from the data shown in d for different concentrations of Rab5(GDP) and GST added to EEA1. The red horizontal region marks the corresponding values for the EEA1_collapsed state on its interaction with Rab5(GTP). The bootstrap α_min (b,e) and λ (c,f) are obtained via 10⁴ and 10⁵ bootstrap samplings of the data, respectively; the open circles and error bars are mean and error of the mean for α_min, and the peak value and error of the peak for λ, respectively, as shown in Supplementary Section 2F3.

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