The invention relates to a recombinant ricin A chain protein system for conditional toxicity expression. A recombinant ricin A chain protein expressed by the recombinant ricin A chain protein system comprises a first polypeptide having 75% or more identity to SEQ ID NO:1, a second polypeptide having 75% or more identity to SEQ ID NO:2, and a plurality of exogenous residues inserted between the first and the second polypeptides. Thus, the activity of a ricin A chain protein can be controlled via the recombinant ricin A chain protein system.本發明係有關於一種條件式表現之重組蓖麻毒素A鍊蛋白系統,其表現一重組蓖麻毒素A鍊蛋白包括:一第一多肽,其與SEQ ID NO:1具有75%以上之一致性;一第二多肽,其與SEQ ID NO:2具有75%以上之一致性;以及,複數個外源殘基,其係插置於該第一多肽與該第二多肽之間。透過本發明之重組蓖麻毒素A鍊蛋白系統可選擇性地控制蓖麻毒素A鍊蛋白之活性表現。
