Binding
domain
Binding
domain
Analyte
a
c
e
f
d
b
Proteolysis
Proteolysis
Analyte
Low FRET
Low FRET
No FRET
No FRET
Atox1
WD4
Zn
2+
High FRET
S208F/
V224L
mutation
High FRET
Low FRET
Low FRET
Protease
substrate
Protease
substrate
Modification
site
Modification
Intermediate FRET
Intermediate FRET
Intermediate FRET
Intermediate FRET
Post-translational
modifications
CFP
YFP
Fig. 4
Representative design formats for FRET-based biosensor: (a) a single binding domain undergoes a conformational change upon binding analyte. (b)
Biosensors to monitor posttranslational modifications. (c) Biosensors to detect protease activity. (d) Biosensors based on an analyte-dependent protein-protein
interaction. (e, f)
FRET-based sensors based on self-associating FPs. (e) Protease sensor. (f) eCALWY sensor for Zn
2+
. Adapted from Tamura et al., with
copyrights [128]
166
U. K. Sukumar et al.