Application of fusion protein 4D5 scFv-dibarnase:barstar-gold complex for studying P185HER2 receptor distribution in human cancer cells.

Overexpression of the P185(HER2) protein determines the malignancy and unfavorable prognosis of ovarian and breast tumors. In this work, the distribution of P185(HER2) in human cancer cells was studied by electron microscopy, using a novel approach. It is based on the interaction between barnase (a ribonuclease from Bacillus amyloliquefaciens) and its specific inhibitor barstar.

Expression of single-chain antibody-barstar fusion in plants.

We successfully cloned and expressed a single-chain antibody (425scFv), that is directed to human epidermal growth factor receptor HER1 (EGFR) in transgenic tobacco plants as a fusion with bacterial barstar gene (425scFv-barstar). Plant-produced recombinant 425scFv-barstar was recovered using barstar-barnase system. Based on barstar-barnase affinity, during purification of the plant-produced 425scFv-barstar, we generated bispecific scFv-antibody heterodimers from individual single-chain fragments initially produced in different host systems with binding activity to both HER1 and HER2/neu tumor antigens.