蓖麻毒素

• A single molecule of rta is able to depurinate 1500 - 2000 ribosomes per minute . ricin b chain ( rtb ) is a galactose - specific lectin which binds to the receptors on cell surfaces , and may enhance rta translocation by forming a pore in the membrane of intracellular organelles . ricin enters the cells by receptor - mediated endocytosis
  内吞进入细胞的蓖麻毒素一部分返回到膜表面，一部分经早期内体至晚期内体，最后在溶酶体中降解，只有一小部分约5到达高尔基体，随后逆转运到粗面内质网，在那里rta才和rtb解离，游离出有催化活性的rta 。