Herein we wish to note our objections to “Substrate-modulated ADP/ATP-transporter dynamics revealed by NMR relaxation dispersion” by Brüschweiler et al.1. The subject of this article is the yeast mitochondrial ADP/ATP carrier AAC3, which we have studied in great detail ourselves. In particular, we have solved its structure by electron2 and X-ray3 crystallography and have studied its interactions with the specific inhibitors atractyloside (ATR) and carboxyatractyloside (CATR) by single-molecule force spectroscopy4. In ref. 1, the authors claim that AAC3 can be refolded to homogeneity from inclusion bodies produced in Escherichia coli using the detergent dodecyl phosphocholine (DPC), better known as Foscholine-12, and that AAC3 is maintained in a folded and active state for the duration of isothermal titration calorimetry (ITC) and NMR experiments. However, in our hands, the presence of DPC leads to immediate loss of tertiary structure and inactivation of AAC3 when the protein is isolated from the inner membrane of mitochondria, where it is folded and active, as shown by functional complementation2,3.