Fig. 7.

Endocytic condensates do mechanical work to deform the membrane and cytosol. (A, Inset) Energy U_total versus membrane invagination d determined from Eq. 1, determined by opposing (ϕ) and favoring (ψ) energy terms. U_total (dark blue), ϕ (black), and ψ (light blue) versus δ. The energy is favorable for δ between about 15 to 80 nm (solid blue line) and unfavorable above 80 nm (dashed blue line). Quantities used to calculate energies are detailed in SI Appendix, Fig. S8A and Tables S2, S3, and S4. (B) Mechanical description of endocytic, condensate-driven membrane invagination. Endocytic condensate (yellow) binds to (wets) the bilayer membrane (black) and drives membrane invagination as the condensate expands to maximize contact with the cytosol (Top to Bottom). Forces balance under a Young-Dupré adhesion gradient (blue lines and arrows) and resistance of the cytosol (gray curved lines).