SPR analysis of the binding of recombinant PIR-B and PIR-A domains to Nogo-66. A and D, SPR profiles of the binding of D1–D6 of PIR-B (A) or PIR-A (D), at various concentrations, to Nogo-66 protein immobilized on sensor chips. Negative control profiles (0 μm D1–D6) were utilized for subtraction from each profile using the Blank Run Subtraction program. B and C, SPR profiles of the binding of D1D2 (B) or D3-D6 (C) of PIR-B, at various concentrations, to Nogo-66 immobilized on sensor chips. Negative control profiles (0 μm D1D2) were utilized for subtraction from each profile using the Blank Run Subtraction program in A. E and F, SPR profiles of the binding of PIR-A D1D2 (E) or D3-D6 (F), at various concentrations, to Nogo-66 immobilized on sensor chips. RU, response units.