Table 1.

Model parameters

Symbol	Description	Value	Source*
$a, b$	Length, width of C2B domain	5 nm, 3 nm	(43)
$c_0$	Monolayer spontaneous curvature (40% PS, 60% PC)	0.02 nm−1	(A)
$d_h$	Hydrophobic interaction length	2 nm	(60, 61)
$E_h^0$	Monolayer-carbon support hydrophobic energy density	0.04 kT/nm2	(B)
${ϵ}^{\text{syt}\text{-}\text{ATP}}$	Syt-ATP binding energy	9.7 kT	(C)
${ϵ}^{\text{syt}\text{-}\text{mono}}$	Syt-monolayer binding energy	18 kT	(D)
${ϵ}^{\text{syt}\text{-}\text{pm}}$	Syt-planar-membrane binding energy	4.9 kT	(D)
${ϵ}^{\text{syt}\text{-}\text{syt}}$	Syt-Syt binding energy	9.5 kT	(E)
${ϵ}^{\text{syt}\text{-}\text{ves}}$	Syt-synaptic-vesicle binding energy	2.2 kT	(D)
$l_p$	Persistence length of Syt oligomer	170 nm	(F)
$R_{\text{bead}}$	Radius of model beads	1.5 nm	(G)
$R_{\text{ves}}$	Vesicle radius	20 nm
$R_0$	Spontaneous radius of curvature of Syt oligomers	13 nm	(F)
$\kappa$	Bending modulus of monolayer (bilayer)	12.5 kT (25 kT)	(H)
$\gamma$	Bilayer membrane tension	0.003 pN/nm	(79, 80)
$\eta$	Viscosity of water	${10}^{-3}$ Pa·s
${\eta }_m$	2D viscosity of lipid bilayers	$3\times {10}^{-9}$ Pa·s·m	(81)
$\lambda$	Debye length at 140 mM salt	0.7 nm	(66)

^*(A) Linear interpolation of spontaneous curvatures of DOPS ($0.07 {\text{nm}}^{-1}$ (82)) and DOPC ($-0.02 {\text{nm}}^{-1}$ (83)), based on the molar fractions of the two components. (B) Deduced in the present work (see Fig. 3 C and D). (C) Experimentally measured in the present work. (D) Calculated in the present work, using measurements of ref. 6 as input. (E) Calculated in the present work, using measurements of ref. 46 as input. (F) Calculated in the present work by fitting Eq. 1 to the experimentally measured Syt ring size distribution in bulk solution (Fig. 2A). (G) Estimated from the C2AB crystal structure (Fig. 1B). (H) Bilayer bending modulus from ref. 84, measured in 100 mM NaCl. Monolayer modulus is assumed half the bilayer value.