Model of Alzheimer precursor protein transmembrane (APP-TM) dimer. The solid state NMR structure of the glycophorin A (GpA-TM) dimer, residues 75–87 (left), and the predicted APP-TM dimer, residue 705–717 (right) are compared. GpA-TM dimer contains the central G79VXXGV84 residues as the packing contacts, whereas APP-TM dimer packing utilizes G709VXXAT714 residues. Sequence alignment of APP-TM and GpA-TM (bottom) shows that residues comprising the packing interface are comparable in both sequences and denoted by capital letters. Exposed residues are shown as lowercase letters.