Demonstration showing the unfolding of green
            fluorescent protein (GFP), resulting in an
            instantaneous disappearance of the green color. GFP was
            denatured by addition of HCl.
          
        
            Refolding of acid-denatured GFP by neutralizing the pH.
          
        
            On and Off of fluorescence-labeled GroES on the
            surface-immobilized GroEL (see Taguchi et al. Nat.
            Biotechnol. 2001 for details)
          
        
            single-molecules of GFP are folded inside the GroEL/ES
            cavity. (see Ueno et al. Mol. Cell 2004 for details)