Alderton J M, Ahmed S A, Smith L A, Steinhardt R A
Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA, USA.
Cell Calcium. 2000 Sep;28(3):161-9. doi: 10.1054/ceca.2000.0144.
Direct microinjection of the clostridial neurotoxins botulinum neurotoxin A light chain or tetanus neurotoxin into cells of a human embryonic kidney cell line significantly reduced calcium entry after depletion of internal calcium stores by cyclopiazonic acid, a reversible inhibitor of the sarcoplasmic-endoplasmic reticular calcium-ATPases. Botulinum neurotoxin A light chain specifically hydrolyzes a synaptosomal-associated protein of 25 kilodaltons (SNAP-25), and tetanus neurotoxin specifically hydrolyzes synaptobrevin-2 (vesicle-associated membrane protein 2, VAMP-2) and cellubrevin (vesicle-associated membrane protein 3, VAMP-3). Since these substrate proteins are required for vesicle docking and fusion, inhibition of store-operated calcium entry by botulinum neurotoxin A light chain and tetanus neurotoxin supports a model in which vesicle fusion is a prerequisite for activation of store-operated calcium entry. Brefeldin A, a fungal metabolite that interferes with vesicle traffic, partially reduced calcium entry following store depletion. The size of the reserve pool of vesicles or parallel vesicle recycling pathways employing brefeldin A-sensitive and brefeldin A-insensitive ADP-ribosylation factors may explain the failure of brefeldin A to completely inhibit store-operated calcium entry.
将肉毒杆菌神经毒素A轻链或破伤风神经毒素直接显微注射到人类胚胎肾细胞系的细胞中，在用环匹阿尼酸（一种肌浆网-内质网钙ATP酶的可逆抑制剂）耗尽细胞内钙储备后，显著减少了钙的内流。肉毒杆菌神经毒素A轻链特异性水解25千道尔顿的突触体相关蛋白（SNAP-25），破伤风神经毒素特异性水解突触小泡蛋白-2（囊泡相关膜蛋白2，VAMP-2）和细胞ubrevin（囊泡相关膜蛋白3，VAMP-3）。由于这些底物蛋白是囊泡对接和融合所必需的，肉毒杆菌神经毒素A轻链和破伤风神经毒素对储存操纵性钙内流的抑制支持了一种模型，即囊泡融合是激活储存操纵性钙内流的先决条件。布雷菲德菌素A是一种干扰囊泡运输的真菌代谢产物，在储存耗尽后部分减少了钙内流。使用对布雷菲德菌素A敏感和不敏感的ADP-核糖基化因子的囊泡储备池大小或平行囊泡回收途径可能解释了布雷菲德菌素A未能完全抑制储存操纵性钙内流的原因。
