A large proportion of biologically relevant processes take place at membranes. Studying the dynamics of these processes in real time and without disturbing the biological system is still a major methodological challenge. A team led by Petra Schwille, director at the MPI of Biochemistry (MPIB), and Nikolas Hundt from the Ludwig-Maximilians-Universität München (LMU) has now developed a new method for this purpose: Mass-Sensitive Particle Tracking (MSPT). Using MSPT, the movements and reactions of individual unlabeled proteins on biological membranes can be determined solely by their mass. The method has been published in Nature Methods.