dBBr is one of the most popular thiol-reactive fluorescent tags, and is widely used to detect various thiol-containing biomolecules such as glutathione in cells. It is fluorogenic upon reacting with thiol-containing molecules. Dibromobimane is a unique fluorogenic crosslinking reagent for proteins because it is unlikely to fluoresce until both of its alkylating groups have reacted. It has been used to crosslink thiols in myosin, hemoglobin, Escherichia coli lactose permease and mitochondrial ATPase. Dibromobimane is also used to probe for the proximity of dual-cysteine mutagenesis sites in ArsA ATPase and to crosslink thiols in actin, myosin and P-glycoprotein.