Cholera toxin

霍乱毒素属于AB5亚基家族毒素。由一个A亚基和五聚体环形式的5个B亚基组成，A亚基负责ADP核糖基化，B亚基负责结合细胞表面受体实现细胞内化。A亚基催化激动型G蛋白（Gαs）的α-亚基的ADP-核糖基化，引起腺苷酸环化酶活性增加、cAMP水平提高。还能ADP-核糖基化信号转导蛋白和微管蛋白。
因对腺苷酸环化酶的影响作用，霍乱毒素与其A亚基常用于研究信号转导机制。此外，霍乱毒素可作为免疫佐剂，通过抑制白介素-12生产来刺激B淋巴细胞和2型辅助性T细胞的免疫应答。无毒性B亚基(CTB)通过结合神经节苷脂GM1吸附细胞，在神经学研究中适合作为小胶质细胞的标记物。还可充当出色的示踪剂，用于轴突运输的免疫组化研究。
应用
来自霍乱弧菌的霍乱毒素已被用作肠毒素 cAMP（环 AMP）测定的阳性对照。它已被用作原发肿瘤和上皮细胞的细胞培养基增补剂。
霍乱弧菌(Vibrio cholerae)来源的霍乱毒素可用于毒素中和试验评估细胞的细胞毒性。
生化/生理作用
毒素包含一个 A 亚基 (27 kDa) 组成，A 亚基 (周围有五个 B 亚基（每个约 12 kDa），该亚基将毒素附着在细胞表面的神经节苷脂 GM1 上。
包装
包装尺寸基于蛋白质含量。
外形
含有 Tris 缓冲盐、氯化钠、叠氮化钠和 EDTA 钠的冻干粉
重悬
在水中复溶为 1 mg/mL 时，溶液将包含 0.05 M pH 7.5 Tris 缓冲盐、0.2 M NaCl、0.003 M NaN3和 0.001 M EDTA 钠。 将复溶的溶液储存在冰箱中。

General description
Cholera toxin is a member of the AB5-subunit family of toxins. It consists of a single A subunit responsible for ADP-ribosylation and five B subunits arranged as a pentameric ring with cell surface receptor binding and internalization functions. The A subunit catalyzes the ADP-ribosylation of the α-subunit of the stimulatory G protein (Gαs), leading to increased adenylyl cyclase activity and cAMP levels. It also ADP-ribosylates transducing and tubulin.

Cholera toxin and its A subunit are commonly used to study signal transduction mechanisms due to their impact on adenylate cyclase. Additionally, cholera toxin acts as an adjuvant by stimulating B lymphocytes and T helper cell type 2 responses by inhibiting interleukin-12 production. The non-toxic B subunit (CTB) attaches to cells by binding to ganglioside GM1, making it a useful label for microglial cells in neurological research. It has also proved to be an excellent tracer for axonal transport studies using immunohistochemical methods.
Application
Cholera Toxin from Vibrio cholerae has been used as a positive control in cAMP (cyclic AMP) assay for enterotoxins. It has been added as a supplement in cell culture media of primary tumors and epithelial cells.
Cholera Toxin from Vibrio cholerae has been used in toxin neutralization assays to assess the cytotoxicity of cells.
Biochem/physiol Actions
Toxin consisting of an A subunit (27 kDa) surrounded by five B subunits (approximately 12 kDa each), which attach the toxin to ganglioside GM1 on the cell surface.
Packaging
Package size based on protein content.
Physical form
Lyophilized powder containing Tris buffer salts, sodium chloride, sodium azide and sodium EDTA
Reconstitution
When reconstituted at 1 mg/mL in water, solution will contain 0.05 M Tris buffer salts, pH 7.5, 0.2 M NaCl, 0.003 M NaN3, and 0.001 M sodium EDTA. Store reconstituted solutions in the refrigerator.