Glucose
is the most important energy source for living animals.
Here, we developed a series of single fluorescent protein (FP)-based
glucose indicators, named as “Green Glifons”, to understand
the hierarchal and mutual relationships between molecules involved
in energy metabolism. Three indicators showed a different EC50 for glucose (50, 600, and 4000 μM), producing a ∼7-fold
change in fluorescence intensity in response to glucose. The indicators
could visualize glucose dynamics in the cytoplasm, plasma membrane,
nucleus and mitochondria of living HeLa cells and in vivo, in the
pharyngeal muscle of C. elegans and could measure
murine blood glucose levels. Finally, the indicators were applicable
to dual-color imaging, revealing the dynamic interplay between glucose
and Ca2+ in mouse pancreatic MIN6 m9 β cells. We
propose that these indicators will facilitate and contribute to in
vivo and multicolor imaging of energy metabolism.