Recombinant toxin fragments

(57) summary polypeptide. Whether polypeptide makes it possible to be conveyed into a target cell, and Or it has the 1st and 2nd domains that enable polypeptide to make the solubility of polypeptide increase, or to be the both and to cut one or more small granule vesicles indispensable to エキソサイ ptosis or protoplasmic membrane interacting protein. Therefore, polypeptide combines the useful characteristic of a clostridial toxin (for example, a Botulin toxin or a tetanus toxin) without the toxicity followed on a natural molecule. Polypeptide target-izes it into a specific cell, and may include again the 3rd domain that makes polypeptide useful in prevention of the エキソサイ ptosis in a target cell. Fused protein containing polypeptide, the nucleic acid which carries out the code of the polypeptide, and the method of producing polypeptide are also offered. The activation by which polypeptide was controlled is possible, and polypeptide may be included in a vaccine and toxin assay.