In the aspirin molecule, continuous periodic charge motions occur during the methyl rotation, in particular between the atoms of the carbon 6-ring (left) and the COOH carboxy unit (right).

Using cryo-electron microscopy, the researchers obtained the 3D structures of human ABCC4 in its apo form (without ligand), bound to three different substrates (the TXA 2 analog U46619, aspirin ...