Patent ID: 7268116

Claim:
A method for generating a secreted disulfide bond-linked trimeric fusion protein, comprising: (a) creating a DNA construct comprising a transcriptional promoter linked to a template encoding a fused protein subunit comprising a signal peptide sequence followed by in-frame fusion to a non-collagenous polypeptide comprising a ligand binding domain, which in turn is joined by in-frame fusion to a mammalian polypeptide which is heterologous from the non-collagenous polypeptide and which is capable of self-trimerizing said fused protein subunit to form said disulfide bond-linked trimeric fusion protein containing three ligand binding domains, wherein said trimeric fusion protein has an increased binding affinity to a ligand than a monomeric ligand binding domain (b) introducing said DNA construct into a eukaryotic cell; (c) growing said host cell in an appropriate growth medium under physiological conditions to allow said fused protein subunits to trimerize into the disulfide bond-linked trimeric fusion protein and to further allow the secretion of the trimeric fusion-protein; and (d) isolating said secreted trimeric fusion protein from the culture medium of said host cell.