Cholera Toxin from Vibrio cholerae ~95% (SDS-PAGE), lyophilized powder, 1 × 105-1 × 106 units/mg protein

Synonym: Cholera enterotoxin, Cholergen

CAS Number: 9012-63-9

MDL Number: MFCD00130776

Packaging
Package size based on protein content.

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.

Unit Definition
One unit increases adenylate cyclase activity 6-fold, measured as [³H]-cAMP present, using approx. 70,000 CHO cells after incubation for 90 min at 37 °C with [³H]-adenine followed by a 15 min incubation with 1 mM 3-isobutyl-1-methylxanthine (IBMX).

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. The A subunit catalyzes ADP-ribosylation of the α-subunit of the stimulatory G protein (Gα_s), reducing GTPase activity and activating the α-subunit. This activation of Gα_s leads to an increase in the activity of adenylyl cyclase, resulting in increased levels of cAMP. Also ADP-ribosylates transducin in the eye rod outer segments, inactivating its GTPase activity. Cholera toxin has also been reported to ADP-ribosylate tubulin. Shown to be a potent mucosal vaccine adjuvant, inducing T helper cell type 2 responses by inhibiting the production of interleukin-12.