FIG. 1.

Schematic representation of the immunotoxin expression cassette in P. pastoris strains. The immunotoxin expression cassette contains a promoter, the preprosequence of α-mating factor, the immunotoxin gene, and the transcription termination sequence for AOX1. The immunotoxin is a multidomain protein containing the DT catalytic domain (DT A), followed by the toxin translocation domain ending at DT residue 390, followed by four Fv domains (VL and VH) of an anti-CD3 antibody, UCHT1. The Fv domains are joined by a 15-amino-acid (G₄S)₃ linker. N-glycosylation and Kex2 cleavage sites are indicated by lollipop symbols and triangles, respectively. S-S, disulfide bridge.