|Budget Amount *help
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2003: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2002: ¥2,200,000 (Direct Cost: ¥2,200,000)
To identify the molecule(s) constituting the receptor for prions, we tried to isolate a prion protein (PrP)-binding protein(s). Full-length mouse PrP, fused with alkaline phosphatase (AP), was used to screen cultured cells for the molecules. All the cells we examined, including neuronal cells, fibroblast cells, and epithelial cells, exhibited strongly stained signals of AP-PrP. Moreover, similar signals were detectable in a neuronal cell line established from PrP-deficient mice. In contrast, AP only showed no signals, indicating the specificity of the binding of AP-PrP. AP was further fused with five deletion mutant PrPs to generate AP-PrP23-120, AP-PrP121-231, AP-PrP23-120AOR, AP-PrP23-90 and AP-PrP50-120, respectively. AP-PrP23-120, containing the N-terminal residues 23-120 of PrP, displayed the same signals, while AP-PrP121-231 comprising AP and the C-terminal residues 121-231 did not. Interestingly, although both AP-PrP23-90 and AP-PrP50-120 showed no AP staining in these cells, AP-PrP23-I120AΔR, lacking the PrP-specific octa-peptide repeats (residues 50-90), showed the strong AP signals. These results suggest that PrP could be associated with the ubiquitously expressed molecule(s) via tow separate N-terminal domains corresponding to the residues 23-50 and 90-120, respectively.