ABSTRACT
The discovery of hybridoma monoclonal antibodies and the expression of recombinant cell-selective peptide hormones provided a wealth of protein ligands for targeting a variety of dysfunctional or neoplastic cells in humans. Structure-function studies of toxins have been greatly aided by the availability of x-ray crystallographic structures for ricin and Pseudomonas exotoxins. With the eventual solution of diphtheria toxin and cholera toxin three-dimensional structures, a wealth of information will be available for hypotheses on mechanisms of toxin action at the molecular level. The clinical applications of genetically engineered toxins are likely to be diverse. In addition to malignant disease, cell-selective ablation may be useful in a number of clinical settings. The intricate mechanism of action of protein toxins has made them interesting tools in cell biology and versatile effector molecules in targeted therapy. In both fields, genetically engineered toxins have opened up a variety of new possibilities and challenging questions.
