Tissue- and cell type-specific modification of prion protein (PrP)-like protein Doppel, which affects PrP endoproteolysis.

A prion protein (PrP)-like protein, Doppel (Dpl) is a homologue of cellular PrP (PrP(C)). Immunoblotting revealed heterogeneous glycosylation patterns of Dpl and PrP(C) in several cell lines and tissues, including brain and testis. To investigate whether the glycosylation and modification of Dpl and PrP(C) could influence each other, PrP gene (Prnp)-deficient neuronal cells, transfected with Prnp and/or the Dpl gene (Prnd), were analyzed by deglycosylation with peptide N-glycosidase F. The modification of Dpl was not influenced by PrP(C), whereas an N-terminally truncated fragment of PrP(C) was reduced by Dpl expression. These results indicated that Dpl was glycosylated in a cell type- and tissue-specific manner regardless of PrP(C), while PrP(C) endoproteolysis was modulated by Dpl expression.