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CPP: Chemische Physik und Polymerphysik

CPP 2: SYMPOSIUM: Dynamics of multi-component fluids II

CPP 2.4: Vortrag

Freitag, 4. März 2005, 12:15–12:30, TU C243

Pattern formation during membrane adhesion — •Thomas R. Weikl — Max Planck Institute of Colloids and Interfaces, Theory Division, 14424 Potsdam

Functional domains in biological membranes are often highly dynamic. An intriguing example are the domain patterns formed during T cell adhesion. The patterns are composed of domains which either contain short TCR/MHCp receptor-ligand complexes or the longer LFA-1/ICAM-1 complexes. During T cell adhesion, the domains evolve in a characteristic pattern inversion: The final T-cell pattern has a bull-eye shape with a central TCR/MHCp domain, whereas the intermediate pattern is inverted with the TCR/MHCp complexes at the periphery of the bull eye. We study the pattern formation dynamics in a statistical-mechanical model for the adhesion of multicomponent membranes. In this model, the domain formation is driven by the length difference between the TCR/MHCp and the LFA-1/ICAM-1 complexes. We obtain several dynamic regimes with distinct domain patterns at intermediate times, and propose a novel self-assembly mechanism for the formation of the intermediate inverted T-cell pattern. This mechanism is based (i) on the initial nucleation of numerous TCR/MHCp microdomains, and (ii) on the diffusion of free receptors and ligands into the cell contact zone. The formation of the final T-cell pattern requires active cytoskeletal transport processes in our model, in agreement with experimental findings.