Application

Cholera toxin B subunit conjugated to peroxidase (CB-HRP) has been shown to be a more effective retrograde and transganglionic tracer for pelvic primary afferents from the urinary bladder than wheat germ agglutinin-horseradish peroxidase or isolectin B4-horseradish peroxidase. Retrograde labeling with CB-HRP has been demonstrated in sympathetic pre-ganglionic neurons as well as in cells of the fastigial nuclei. It is also an effective anterograde tracer for the study of axonal and terminal labeling in the brain stem. Cholera Toxin B subunit has been used:In the isolation of lipid rafts and analysis of B-cell receptor distribution, signaling and ubiquitination.In the staining of lipid rafts in brain tissues.As a transganglionic tracer to determine the central projections of the anterior ethmoidal nerve in rat.

Biochem/physiol Actions

Cholera toxin gains entry into the host cell via host′s glycolipid transport pathway. The toxin is an essential factor for the pathogenesis of cholera. The ToxR gene is responsible for the activation of the expression of the gene coding cholera toxin.

The cholera toxin B subunit is used for track tracing in neurological research, taking advantage of GM1 ganglioside binding and retrograde transport. Tissue culture cells treated with cholera toxin are not killed and tissues of animals do not become necrotic.

Caution

Do not freeze.

General description

Cholera toxin is produced by Vibrio cholerae species, and the gene ctxB (cortexillin II) encodes the B subunit of the toxin. Cholera toxin belongs to the AB2 family of toxins. It is composed of a single A subunit of 28 kDa and five B subunits of 11 kDa.

Packaging

Prepared and packaged using aseptic technique and sealed under vacuum.

Physical form

Lyophilized powder containing 11-13% protein with the balance consisting of phosphate buffer and sodium chloride.

Reconstitution

Reconstitution of the vial with 100 µl of water will yield a final solution containing: 1 mg/mL HRP, 0.45 mg/ml CTB, 10 mM phosphate buffer and 150 mM NaCl. Swirl bottles gently during reconstitution. Avoid vigorous pipetting of solutions that may lead to foaming. Solutions can be sterile filtered through a 0.2 µm filter. Store the reconstituted solutions at 2-8 °C.

Specificity

HRP activity exceedes 100 pyrogallol units per mg of HRP in the CTB-HRP conjugate. Activity: 10-30 pyrogallol units per vial.

Unit Definition

Unit definition: One pyrogallol unit converts 1 mg of pyrogallol to purpurogallin in 20 seconds at pH 6.0 at 20 °C.