GroEL-protein interactions were characterized by stable isotope-assisted nuclear magnetic resonance (NMR) spectroscopy using chemically denatured bovine rhodanese and an intrinsically disordered protein, alpha-synuclein, as model ligands. NMR data indicated that proteins tethered to GroEL remain largely unfolded and highly mobile, enabling identification of the interaction hot spots displayed on intrinsically disordered proteins. (c) 2013, The Society for Biotechnology, Japan. All rights reserved.