Morphological and steroidogenic changes in cultured adrenal tumor cells induced by a subunit of cholera enterotoxin

A purified subunit of the cholera enterotoxin molecule was found to have morphological and steroidogenic inducing effects similar to those induced by the native enterotoxin on monolayer tissue cultures of Y1 adrenal tumor cells, although 1,000 times more subunit than toxin (weight basis) was required for maximal effects. In contrast to the whole toxin, the effects of the active subunit could not be prevented by prior incubation with either Gm1 ganglioside or with antibodies directed against choleragenoid (the binding subunit). These results suggest that different receptor sites may exist on cells for the binding and for the active subunits of cholera enterotoxin and/or that the active toxin fragment may exert its effects after gaining access to the intracellular compartment.