The present invention provides a fusion protein comprising (1) the extracellular domain of glycoprotein VI or a variant thereof that is functional for binding to collagen and (b) the Fc domain of the immunoglobulin or a function-conservative part thereof, characterized by a polypeptide chain having an amino acid sequence as shown in FIG. 7 and whereby the fusion protein is obtainable by a process which provides the fusion protein in the form of a specific dimer.