Hybrid protein

Abstract

A hybrid protein including protein fragments joined together by peptide bonds, the hybrid protein including, in sequential order, beginning at the amino terminal end of the hybrid protein, (a) the enzymatically active Fragment A of diphtheria (b) a fragment including the cleavage domain 1.sub.1 adjacent the Fragment A of diphtheria toxin, (c) a fragment including at least a portion of the hydrophobic domain of Fragment B of diphtheria toxin and not including the generalized eukaryotic binding site of the Fragment B, and (d) a fragment including a portion of a cell-specific polypeptide ligand, the portion including at least a portion of the binding domain of the polypeptide ligand, the portion of the binding domain being effective to cause the hybrid protein to bind selectively to a predetermined class of cells to be attacked by the enzymatically active Fragment A.

Dependencies are inferred from the claim text.