Before revision:  an isotropic and uniform distribution of orientations of the spin label in space was found due to the large exposure of the activation loop to the solvent water. A hydrodynamic approach was employed to determine the rotational protein tumbling, while the internal motion of the spin probe was determined from 94 GHz measurements that reflect the fast motions. The theoretical 9 GHz EPR spectra were calculated using configurations representing interactions between MTSL and water and the tyrosine residue 208 in the C-lobe and the comparison with experimental EPR spectra produced fits that successfully reproduced the experimental spectra in agreement with the average structures obtained from the MD trajectories showing the MTSL exposed to the solvent and probing the C-lobe of the protein .
After revision:  an isotropic and uniform distribution of orientations of the spin label in space was found due to the large exposure of the activation loop . The 9 GHz EPR spectra were calculated using configurations representing interactions between MTSL and water and the tyrosine residue 208 in the C-lobe and the comparison with experimental EPR spectra produced fits that successfully reproduced the experimental spectra in agreement with the average structures obtained from the MD trajectories showing the MTSL exposed to the solvent and probing the C-lobe of the protein .