Abstract: The present invention provides a polypeptide comprising an antigen binding domain which binds to an antigen present in cartilage tissue, and also provides use of the polypeptide. The polypeptide of the invention is useful for penetrating and/or retaining a desired substance in the cartilage tissue for a long period. The present invention further relates to a polypeptide comprising (i) an antigen binding domain which binds to a molecule in a cartilage tissue, and (ii) a carrying moiety having an inhibiting domain that inhibits the antigen binding activity of the antigen binding domain, and having a longer half-life than that of the antigen binding domain existing alone, and a pharmaceutical composition comprising the polypeptide. The present invention further relates to methods for producing and screening for the polypeptide.

Abstract: The present invention relates to a polypeptide comprising an antigen binding domain and a carrying moiety having an inhibiting domain that inhibits the antigen binding activity of the antigen binding domain, and having a longer half-life than that of the antigen binding domain existing alone, methods for producing and screening for the polypeptide, a pharmaceutical composition comprising the polypeptide, methods for producing and screening for an antigen binding domain whose antigen binding activity is inhibited by associating with particular VL, VH or VHH, and a fusion polypeptide library including an antigen binding domain whose antigen binding activity is inhibited by associating with particular VL, VH or VHH.