| 摘要 |
Targeting molecules for use in delivering imaging agents to epithelial tissue are disclosed. Upon delivery, the imaging agent(s) may remain within an epithelial cell or may undergo transepithelial transport via transcytosis. The targeting molecules may be used, for example, for diagnostic techniques. The targeting molecule is a polypeptide, which may be produced by recombinant methods, that forms a closed covalent loop, contains at least three peptide domains having beta -sheet character which are separated by domains lacking beta -sheet character, specifically binds to a basolateral factor attached to a basolateral domain of an epithelial surface causing uptake of a linked imaging agent into cells of the epithelial surface, and is not a full length dimeric Iga. Preferably, the polypeptide is a J chain polypeptide, or a J chain polypeptide linked to an immunoglobulin heavy chain without an immunoglobulin light chain.
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