Recombinant cell surface capture proteins and detection molecules that are useful for isolating and detecting cells that produce a secreted heterodimeric protein of interest (POI) that has an immunoglobulin CH3 domain and/or substituted CH3 domain are provided. Recombinant cell surface capture proteins and detection molecules that isolate and detect bispecific antibodies are also provided. The invention also provides recombinant antigen-binding proteins that are capable of recognizing and binding to proteins of interest that contain a CH3 domain and/or a modified CH3 domain, such as a CH3 domain with or without amino acid substitutions at H95 and Y96 (IMGT).
