Voorheis H P, Bowles D J, Smith G A
J Biol Chem. 1982 Mar 10;257(5):2300-4.
Bloodstream forms of the African trypanosomes undergo antigenic variation in their mammalian host. This process involves removal of the existing variant coat protein and its replacement with another. The mechanism by which the surface coat protein is released to the external supporting medium has been shown to depend in vitro specifically on the presence of calcium ions together with the calcium ionophore. A-23187, and to be inhibited by Zn2+. Release of the surface coat protein was not stimulated by conditions designed to alter the plasma membrane potential or the major ionic gradients across that membrane. Release could be stimulated by inhibiting the energy metabolism of these glycolysing cells with 2-deoxyglucose, which probably prevents the energy-dependent mechanisms that normally keep the cytoplasmic Ca2+ concentration low. These results and the finding that the release process was strongly temperature dependent suggested the possible mediation of some as yet undefined enzymatic reaction.
非洲锥虫的血流型在其哺乳动物宿主体内会发生抗原变异。这一过程涉及去除现有的变异表面糖蛋白并用另一种糖蛋白取而代之。已表明，表面糖蛋白释放到外部支持介质的机制在体外具体取决于钙离子与钙离子载体A-23187的存在，并受到Zn2+的抑制。旨在改变质膜电位或跨该膜的主要离子梯度的条件不会刺激表面糖蛋白的释放。用2-脱氧葡萄糖抑制这些进行糖酵解的细胞的能量代谢可刺激释放，这可能会阻止通常使细胞质Ca2+浓度保持在低水平的能量依赖性机制。这些结果以及释放过程强烈依赖温度这一发现表明，可能存在某种尚未明确的酶促反应介导这一过程。
