Fig 9. Fine mapping of the epitope recognized by C7 scFv.

(A) Alignment of the human and mouse Lu amino acid sequences. Amino acids that are identical across species are connected with vertical lines. Ser²⁴², Glu²⁴⁵, Arg²⁴⁷, and His²⁵⁷ in Lu-Fc were substituted with the corresponding mouse residues, Asp, Ser, Gln, and Arg, respectively. Gln²⁴⁰ in MsLu-Fc was substituted with Arg, the corresponding human residue. (B) Purification of the mutant proteins. The mutant proteins purified from conditioned media were subjected to SDS-PAGE on a 7.5% gel. (C) ELISA using C7 scFv mixed with various recombinant proteins. The mutant proteins were mixed with the diluted C7 scFv and were added to the wells coated with Lu-Fc. C7 scFv did not react with R247Q-Fc, indicating that Arg²⁴⁷ is required for immunoreactivity.