Monomeric and dimeric antibody-fragment fusion proteins

A dimeric protein comprising two monomeric fusion proteins in a noncovalent interaction, wherein

• the orientation of the monomeric fusion proteins in the dimer is identical with respect to their N- and C-termini,
• the noncovalent interaction between monomeric fusion proteins is formed between interactive peptides on each monomeric fusion protein, which peptides are identical with each other or nonidentical, and
• each monomeric fusion protein is a monomeric antibody-fragment fusion protein comprising:
• (a) a single chain Fv (scFv) fragment of an antibody,
• (b) a linker peptide, and
• (c) a first interactive peptide comprising a first amphiphilic helical peptide containing up to 50 amino acids, said first amphiphilic helical peptide being capable of forming a dimer with a second amphiphilic helical peptide by noncovalent interaction,
• wherein the C-terminus of (a) is fused with the N-terminus of (b), and the C-terminus of (b) is fused with the N-terminus of (c) and,
• with the proviso that if either monomeric fusion protein comprises a helical peptide which is a jun-zipper, the other monomeric fusion protein may not comprise a helical peptide which is a jun-zipper.