* Cholera toxin is an AB toxin that has five B subunints and one A subunit. The toxin acts by the following mechanism:  First, the B subunit ring of the cholera toxin binds to GM1 gangliosides on the surface of target cells. If a cell lacks GM1 the toxin most likely binds to other types of glycans, such as Lewis Y and Lewis X, attached to proteins instead of lipids.