Mass spectrometric detection of protein nanoclusters: the invisible intermediates of phase separation

Abstract

Phase separation of biomolecules, including intrinsically disordered proteins, is an underlying physical process behind cellular condensate formation. To increase mechanistic understanding of its initial stages, we demonstrate the application of charge detection mass spectrometry to characterise the mass dispersion of protein nanoclusters that represent intermediates in this important biophysical process. We detect polydisperse clusters of 1-280 protein molecules (64 kDa-18.4 MDa), that are currently invisible to most analytical techniques.