METHOD FOR MEASUREMENT OF CONCENTRATION OF ANTIGEN
The object of the present invention is to provide a detection method that can detect an antigen even if the target antigen has a low molecular weight in a simpler, more efficient, and more stable manner and with higher sensitivity. The detection of the antigen is carried out by using a fusion protein comprising a polypeptide containing a V H domain of an antibody
a given protein
a linker peptide
a partner protein having an activity of binding to the protein and capable of detecting binding to the protein
and a polypeptide containing a V L domain of the antibody
in this order or in inverse order to this order, wherein the presence or absence of the binding of the polypeptide containing a V H domain and the polypeptide containing a V L domain to the antigen induces the presence or absence of the binding of the protein and the partner protein.