Fig. 5.

Left panel: schematic view of three major forces controlling the primary phase of cell adhesion – (i) the short range attractive lock-and-key forces between CAM molecules act within the typical range of h ~ 15 nm. (ii) The repulsive forces mediated by membrane proteins with large extracellular domains (for example CD 45, CD 43 and ICAM) or hyaluronic acid (HA) molecules anchored to membrane receptors of the CD 44 family. (iii) Elastic stress caused by the length mismatch (H ≠ h). The range of the deformation is determined by the persistence length ξ_p (eqn (3)). Right panel: phase diagram for adhesion. The ordinate shows the normalized bending energy and the abscissa the volume fraction of ligands. U_c marks the lower critical point of the miscibility gap. Above U_c, long range attraction of the isolated CAM–CAM pairs leads to the formation of microdomains. Bellow U_c a homogeneous state appears, which is realized for very low CAM concentrations and small height mismatches (H − h ≈ 0).