Redfield and Roberts investigated the dynamics of phospholipids from C and 31 P fieldcycling relaxometry. Field-cycling P NMR of phospholipids in vesicles and micelles demonstrated that increased phospholipid motion of zwitterionic phosphatidylcholine (PC) contributed to enhance phosphatidylinositol-specific phospholipase C (PLC) activation. This insight underscores the importance of lipid-protein interactions in membrane function.