Extended Data Fig. 2. GEM-Halo-FRB fusion expression screen.

Constructs were transiently expressed in HeLa cells under a cytomegalovirus (CMV) promoter and labeled with Halo-TMR. The transfections resulted in a range of GEM expression levels. Boxed labels in pink indicate constructs that give rise to predominantly uniformly sized fluorescent puncta. Asterisks indicate constructs with soluble protein localisation. Daggers indicate aggregation, which was more prominent at high expression levels for some constructs. Dashed lines mark the cell nucleus based on Hoechst staining imaged in a separate channel. Low expression examples are displayed with identical contrast settings with respect to one another. High expression examples from the same experiment, defined here as cells with five times brighter fluorescence, are displayed with identical contrast settings. Representative images, experiment performed twice with similar results.