OVEREXPRESSION OF ACTIVE SYRIAN GOLDEN-HAMSTER PRION PROTEIN PRPC AS A GLUTATHIONE-S-TRANSFERASE FUSION IN HETEROLOGOUS SYSTEMS

This article describes a procedure which permits for the first time th e isolation of the prion protein PrPc from the Syrian golden hamster i n heterologous systems. Using a glutathione S-transferase (GST) fusion approach, milligram amounts of stable, soluble, and homogeneous GST:: PrPc protein were obtained in Escherichia coil and with baculovirus-in fected insect cells. Authentic PrPc was released from the immobilized fusion protein by direct cleavage with thrombin. GST::PrPc expressed i n these two expression systems and also authentic PrPc released by thr ombin cleavage were recognized by a polyclonal antibody directed again st amino acids 95 to 110 of the golden hamster PrPc protein. GST::PrPc was not detected by a monoclonal antibody recognizing the region enco mpassing amino acids 138 to 152 of the human prion protein. The fusion protein was sensitive to proteinase K digestion, demonstrating that t he cellular rather than the proteinase K-resistant scrapie isoform was produced.