Possible involvement of calpain-like activity in normal processing of cellular prion protein

▶ The life time of PrPC is cleaved as a normal protein or it is uncleaved as an abnormal protein, PrPSc. ▶ This is the first report of real-time imaging of protein cleavage process of PrP. ▶ The real-time imaging revealed that calpastatin drastically inhibited endoproteolysis of PrPC. ▶ Calpain-like activity mediates normal processing of PrPC.