The metabolism and imaging in live cells of the bovine prion protein in its native form or carrying single amino acid substitutions

Prion diseases are probably caused by an abnormal form of a cellular glycop rotein, the prion protein. Recent evidence suggests that the prion strain c ausing BSE has been transmitted to humans, thereby provoking a variant form of Creutzfeldt-Jacob disease. In this work, we analyzed the behavior of no rmal and malformed isoforms of the bovine PrP in transfected mammalian cell lines. Biochemical and immunocytochemical assays were complimented with im aging of live cells expressing fusion constructs between PrP and GFP. Bovin e homologues of human E200K and D178N (129M) mutations were used as models of pathogenic isoforms. We show that the GFP does not impair the metabolism of native and mutant bPrPs and is thus a valid marker of PrP cellular dist ribution. We also show that each amino acid replacement provokes alteration s in the cell sorting and processing of bPrP. These are different from thos e ascribed to both murine mutant homologues. However, human and bovine PrPs carrying the D178N genotype had similar cellular behavior.