Secondary-structure prediction revisited: Pβ and Pc represent structures of amyloids and aid elucidating phenomena in interspecies transmissions of prion.

Prion is a unique infectious agent which consists solely of abnormally-folded prion protein (PrPSc) but possesses virus-like features, e.g. existence of strain diversity, adaptation to new hosts and evolutionary changes. These biological phenomena were attributed to the structural properties of PrPSc due to lack of genetic material of prion. Therefore, regardless of incompatibility with high-resolution structural analysis, many structural models of PrPSc have been hypothesized based on limited structural information and, recently, models consisting solely of {beta}-sheets and intervening loops/kinks have been suggested, i.e. parallel in-register {beta}-sheet models and {beta}-solenoid model.