Experimental Measurement of Three-Body Interactions of Lipid Membrane-Deforming Colloidal Spheres

For many cell functions, a concerted effort of several membrane proteins is needed, for example in signaling, division, and endocytosis. Besides specific protein-protein interactions and interactions with the cytoskeleton, protein organization in membranes is thought to be driven by a universal interaction force arising from membrane deformations. However, the small size and the inherent complexity of the proteins’ shape and interactions make it difficult to experimentally measure this interaction. We recently developed an experimental model system consisting of Giant Unilamellar Vesicles and adhesive colloids which allows us to quantitatively study these interactions. Here, we use this setup to investigate the many-body interactions that arise from three membrane-deforming spheres on a GUV. We quantify their interactions and arrangements and conclude that there exist two favorable configurations on the membrane: (1) a linear, and (2) a triangular configuration. These observations demonstrate the non-additive nature of membrane-deformation induced interactions.