Genetically-encoded FRET-based sensors for monitoring Zn(2+) in living cells.

Genetically-encoded fluorescent sensor proteins are attractive tools for studying intracellular Zn(2+) homeostasis and signaling. Here we provide an overview of recently developed sensors based on Förster Resonance Energy Transfer (FRET). The pros and cons of the various sensors are discussed with respect to Zn(2+) affinity, dynamic range, intracellular targeting and multicolor imaging. Recent applications of these sensors are described, as well as some of the challenges that remain to be addressed in future research.