Another protein involved in Alzheimer’s disease is called tau, and it is located inside the neuron. To function, a protein must have a three-dimensional shape. It assumes this shape by means of folding, a process in which the amino acids that make up the protein twist themselves into a very specific conformation. Think of it as exquisitely complicated origami. When a molecular defect causes the tau protein to misfold, it forms toxic clumps (fig. 5.8) that create neurofibrillary tangles.
