Herein is reported a recombinant fusion polypeptide comprising an antibody heavy chain variable domain, a multimerization domain and an antibody light chain variable domain, wherein the antibody heavy chain variable domain is fused (either directly or via a first (peptidic) linker) to one terminus of the multimerization domain, the antibody light chain variable domain is fused (either directly or via a second (peptidic) linker) to the respective other terminus of the multimerization domain, and the antibody heavy chain variable domain or the antibody light chain variable domain has a (intra-peptidic) disulphide bond to the multimerization domain.