FIGURE 14.

Greater flexibility of the L-selectinN138G hinge augments catch bonds and flow-enhanced rolling. Micro-spheres coated with matched densities of L-selectin or L-selectinN138G were perfused through a flow chamber containing immobilized PSGL-1 (a, c, e, and g) or 6-sulfo-sLe^x (b, d, f, and h). The force dependence of the tether lifetime is shown in (a and b); the solid lines indicated the pseudoatom model fits of the sliding-rebinding mechanism.⁸,⁹ The mean rolling velocities shown in (c and d) represent the mean ± SD from five experiments. The mean stop time (e and f) or fractional stop time (g and h) represent analyses of thousands of rolling steps collected from 10−15 microspheres rolling for 1 s at each wall shear stress for each pair of selectin—ligand interactions. Reproduced from Lou et al.⁸