Résumé
ObJective To locate the cysteine-rich domains(CRD) of murine 4-1BB binding to its natural ligand. Methods A serial soluble extracellular CRDs of routine 4-1BB and 4-1BBL fusion proteins was constructed and prepared. The binding of purified 4-1BB-Igs to 4-1BBL and 4-1BB monoclonal antibody were tested using ELISA assay and Western blot analysis. Blocking experiment with 4-1BBL and 4-1BB mon-oclonal antibody was performed by ELISA assay. Results All truncated overlapped proteins containing ex-tracellular CRD Ⅱ of murine 4-1BB were able to bind to 4-1BBL by ELISA assay, excepting the CRD Ⅰ do-main alone. A 4-1BB monoclonal antibody proved to block the interaction of 4-1BB and 4-1BBI, was also able to bind to CRD Ⅱ. Conclusion Murine 4-1BBL whose specificity was mapped to CRD Ⅱ of 4-1BB ex-tracellular region with a possible conformational structure.