cal chalice-like structure into which the NTD could insert its interfacial ganglioside-binding domain (Fig. 7 ). The formation of this trimolecular complex was progressive, starting with a conformational rearrangement of the first ganglioside–NTD complex triggered by the second GM1 molecule. The energy of interaction of the new complex was consistently increased by 37%, reaching an estimated value of -137 kJ.mol−1. At this stage, a