Experimental tuning of Ras-LOCKR-S. Left, predicted structure of Ras-LOCKR-S with mutations highlighted. Right, heat maps of Ras-LOCKR-S with latch:cage or key:cage weakening mutations. FRET ratios (yellow/cyan) before (background) and after (maximum) 100 ng ml −1 EGF stimulation ( n = 14 cells per condition) in 293T cells transiently expressing Ras-LOCKR-S. Dynamic range equals maximum FRET ratio (EGF) minus basal FRET ratio. The colored boxes in EGF-stimulated dynamic range heat map correspond to the constructs tested in f .
