Prion: the chameleon protein.

From Creutzfeldt-Jakob disease (CJD) to variant CJD through Gerstmann-Sträussler-Scheinker syndrome, kuru and fatal familial insomnia, the journey leading to current understanding of the basic aspects of human prion diseases has been full of unexpected, but often dramatic and always fascinating twists. Recent progress in modeling prion diseases and characterization of the various prion protein forms reveal that such a wide spectrum of the diseases is associated with the chameleon-like conformational features of prions.