Instead of increasing the range of the intersurface repulsion, the presence of the bulky neoglycolipid on the target membrane resulted in the protein monolayers jumping into contact with the membranes, at distances that were smaller than the thickness of unbound protein, D T . Figure 2 shows the forceÀdistance curve measured between the 6-repeat form of DC-SIGNR and a 5 mol % Man 9 GlcNAc 2 -DPPE monolayer. The surfaces jump into adhesive contact (left pointing arrow) from membrane separations D J . In force measurements, surfaces jump to contact when the gradient of the intersurface potential exceeds the spring constant. 26 The jump-in distance D J , trajectory, and final resting position at contact D C are determined by the spring constant, which was 205 N/m in these measurements. Here, the normalized force at D C is slightly negative (∼À0.1 mN/m). The equilibrium separation D eq is at F = 0 where the attractive and repulsive forces balance.