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3Cpro wt CM IEALFQ↓GPPKFR

3Cpro mut CM IEKLFQ PPPKFR

GFP2 DsRed2

Figure S1. Diagram depicting the FRET probe for detecting the 3Cpro activity in vivo. Composition and linear arrangement of the GFP2 and DsRed2 reporters are illustrated. The 3Cpro cleavage motif (3Cpro wt CM) and the corresponding mutant motif (3Cpro mut CM) in the linker are shown, with the arrow indicating the scissile bond of 3Cpro and the underlined residues representing the mutations in the P4 and P1’ positions.