Conformational restraint as a strategy for navigating towards lysosomes.

Using the conformational restraint strategy, we developed a hydrazonate-derived coumarin into a lysosome targeting probe for imaging native formaldehyde at the subcellular level. Using this probe, we observed the overproduction of formaldehyde in lysosomes when cells were treated with endoplasmic reticulum (ER) stress inducers, suggesting the involvement of formaldehyde in protein misfolding.