Probing the influence of mutations on FUS condensates, one molecule at a time.

Protein aggregation and phase separation appear to play important roles in diseases like amyotrophic lateral sclerosis (ALS) and frontotemporal lobar dementia (FTLD), but the interplay between different participating molecular events-which may facilitate or inhibit one another-can be difficult to study by conventional ensemble methods. In a recent study, Kevin Rhine and co-workers make use of point mutations to demonstrate the contrasting behaviour of condensates arising from Glycine and Arginine FUS mutants using single molecules fluorescence measurements.