Dimeric molecular complexes comprising a first and second fusion protein, wherein each fusion protein comprises from its N to C terminus (a) a CH4 dimerization domain of an M2" IgE splice variant, (b) an amino acid linker which is covalently bound to the CH4 dimerization domain and (c) an extracellular domain of a type II membrane receptor, wherein the molecular complex comprises a disulfide bond between cysteine residues within the C terminal M2" IgE splice variant CH4 dimerization domains of each of the two fusion proteins useful for therapeutics and diagnostics.
