Label-free tracking and mass measurement of single proteins on lipid bilayers

We introduce dynamic mass photometry, a method for label-free imaging, tracking and mass measurement of membrane-associated proteins. Our method enables quantitative studies of their mobility, membrane affinity and interactions at the single molecule level. Application to the membrane remodelling GTPase dynamin1 reveals heterogeneous mixtures of oligomers suggesting that the fundamental building block for oligomerisation is a dimer, challenging current tetramer-centric models. Dynamic mass photometry has the ability to transform our approach to studying biomolecular mechanisms in and on lipid bilayers. ### Competing Interest Statement P. K. is founder of and shareholder at Refeyn Ltd. M.S.K. is a consultant at Refeyn Ltd. G.Y. is a shareholder of Refeyn Ltd. E.D.B.F. declares no competing interests.