Significance Intrinsically disordered proteins (IDPs) have attracted significant attention due to their roles in crucial cellular processes. NMR is the only technique that allows the study of IDPs at atomic-level resolution. However, narrow chemical shift dispersion, rapid exchange with solvent, and high proline content challenge conventional ¹ H-detected experiments. Here, we report the development of a suite of 3D experiments based on ¹⁵ N direct detection that harnesses the slow relaxation and the larger chemical shift dispersion of ¹⁵ N nuclei for complete backbone assignment of IDPs, including proline residues, which are critical to the study of IDPs. Using this approach, we have assigned the regulatory domain of NFATC2 and have identified a likely mechanism by which 14-3-3 proteins regulate NFAT nuclear translocation.