Diphtheria toxin receptor-binding region

An essentially pure preparation of nucleic acid, said nucleic acid comprising a sequence encoding a polypeptide consisting of:

• a) amino acids 379-535;
• b) amino acids 380-535;
• c) amino acids 381-535;
• d) amino acids 382-535;
• e) amino acids 383-535;
• f) amino acids 384-535;
• g) amino acids 385-535;
• h) amino acids 386-535;
• i) amino acids 496-512;
• j) amino acids 379-512;
• k) amino acids 380-512;
• l) amino acids 381-512;
• m) amino acids 382-512;
• n) amino acids 383-512;
• o) amino acids 384-512;
• p) amino acids 385-512;
• q) amino acids 386-512;
• r) amino acids 496-535;
• or
• s) amino acids 496-524 (all of FIG. 5 (SEQ ID NO:
• 1)), wherein said nucleic acid does not encode an amino acid sequence corresponding to amino acids 291 to 378 of FIG. 5 (SEQ ID NO:1) immediately adjacent to the amino terminal end of said polypeptide and said polypeptide is capable of binding a diphtheria toxin sensitive cell.

A method of making a polypeptide consisting of

• a) amino acids 379-535;
• b) amino acids 380-535;
• c) amino acids 381-535;
• d) amino acids 382-535;
• e) amino acids 383-535;
• f) amino acids 384-535;
• g) amino acids 385-535;
• h) amino acids 386-535;
• i) amino acids 496-512;
• j) amino acids 379-512;
• k) amino acids 380-512;
• l) amino acids 381-512;
• m) amino acids 382-512;
• n) amino acids 383-512;
• o) amino acids 384-512;
• p) amino acids 385-512;
• q) amino acids 386-512:
• r) amino acids 496-535;
• or
• s) amino acids 496-524 (all of FIG. 5 (SEQ ID NO:
• 1)), comprising synthesizing said polypeptide biologically by expression from genetically-engineered DNA encoding said polypeptide.

A DNA encoding a fusion polypeptide consisting of (1) a first sequence corresponding to

• a) amino acids 379-535;
• b) amino acids 380-535;
• c) amino acids 381-535;
• d) amino acids 382-535;
• e) amino acids 383-535;
• f) amino acids 384-535;
• g) amino acids 385-535;
• h) amino acids 386-535;
• i) amino acids 496-512;
• j) amino acids 379-512;
• k) amino acids 380-512;
• l) amino acids 381-512;
• m) amino acids 382-512;
• n) amino acids 383-512;
• o) amino acids 384-512;
• p) amino acids 385-512;
• q) amino acids 386-512;
• r) amino acids 496-535;
• or
• s) amino acids 496-524 (all of FIG. 5 (SEQ ID NO:
• 1)), linked by a peptide bond to (2) a second sequence, provided that said fusion polypeptide does not comprise amino acids 291 to 378 of FIG. 5 (SEQ ID NO:1) immediately adjacent to the amino terminal end of said first sequence.