We aim to understand life processes that involve deformation and remodeling of membranes, such as viral infection, cell-cell fusion in fertilization, and secretion of neurotransmitters by exocytosis. In order to gain insight into membrane remodeling in such processes, we use mechanical single-molecule techniques: Optical Tweezers in combination with confocal fluorescence microscopy and Atomic Force Microscopy (AFM). These tools allow us to measure membrane mechanical properties and the interactions between membranes and proteins in bio-mimetic model systems and cells.