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. 2012 Dec 10;110(1):E15–E22. doi: 10.1073/pnas.1214638110

Fig. 1.

Fig. 1.

Depiction of algal-expressed immunotoxin proteins. (A) Single-chain antibody (scFv) directed against the CD22 cell-surface antigen made by linking the variable domains of the heavy- and light-chain antibodies with a glycine-serine linker. (B) The CD22-scFv is genetically linked to P. aeruginosa exotoxin A domains 2 and 3. Removal and replacement of domain Ia from exotoxin A with an antibody allows cancer cells to be targeted specifically. (C) The CD22-scFv genetically fused to the hinge and constant domains of an IgG1 and to exotoxin A domains 2 and 3 to create a construct that forms a homodimer through disulfide bonds formed between hinge regions. This fusion allows the molecule to have two binding domains as well as two toxin molecules.