Expression and activity of a recombinant chimeric protein composed of pokeweed antiviral protein and of human interleukin-2

The pokeweed antiviral protein (PAP) has already been used to chemically construct immunotoxins, Here we tested the recombinant approach for the production of PAP-containing cytotoxic fusion-proteins, A cDNA encoding a mutated PAP (PAP9), which is expressed at high levels in bacteria, was fused to human interleukin-2 (IL-2) cDNA, The resulting PAP9-IL-2 protein was as active as the free PAP9 in inhibiting an eukaryotic cell-free translation system, Only the chimeric protein desaminated the 28S rRNA and inhibited translation of the CTLL-2 cell line which expresses the IL-2 receptor, These results show that PAP is a suitable toxin for the production of recombinant immunotoxins.