Proteolytic fragmentation of the murine prion protein: role of Tyr-128 and His-177.
The prion protein (PrP) has been proposed to display sequence and structural similarities to membrane-anchored signal peptidases [Glockshuber et al. (1998) FEBS Lett. 426, 291-296]. We have investigated the role of Tyr-128 and His-177 in the proteolytic fragmentation of murine PrP by mutating these residues to Phe and Leu, respectively, and expressing the resultant mutants in the human neuroblastoma SH-SY5Y. Both PrP-Y128F and PrP-H177L were expressed at the cell surface as glycosyl-phosphatidylinositol-anchored forms and were localised in detergent-insoluble membrane domains similar to wild type PrP. Following deglycosylation, the 19 kDa proteolytic fragment PrP-II was present in cells expressing either mutant, indicating that Tyr-128 and His-177 are not involved in the proteolytic fragmentation of PrP.
Perera
W S
WS
School of Biochemistry and Molecular Biology, University of Leeds, Leeds, UK.
Hooper
N M
NM
D000818:Animals; D019286:Endopeptidase K; D006031:Glycosylation; D017261:Glycosylphosphatidylinositols / Q000096:biosynthesis / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry*; D006801:Humans; D007930:Leucine / Q000737:chemistry; D008565:Membrane Proteins / Q000096:biosynthesis / Q000737:chemistry*; D051379:Mice; D009154:Mutation; D009447:Neuroblastoma; D010649:Phenylalanine / Q000737:chemistry; D011328:Prions / Q000096:biosynthesis / Q000737:chemistry*; D012697:Serine Endopeptidases / Q000737:chemistry; D014162:Transfection; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases; D014443:Tyrosine / Q000737:chemistry*
D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; D011328:Prions; D014443:Tyrosine; D010649:Phenylalanine; D006639:Histidine; D010738:Type C Phospholipases; D012697:Serine Endopeptidases; D019286:Endopeptidase K; C026515:type I signal peptidase; D007930:Leucine