Insertion of ganglioside GM1 into rat glioma C6 cells renders them susceptible to growth inhibition by the B subunit of cholera toxin

The B subunit of cholera toxin does not affect the growth of rat glioma C6 cells which are deficient of its receptor, ganglioside G_M1. Insertion of ganglioside G_M1 into the plasma membrane of C6 cells renders them susceptible to inhibition of DNA synthesis by the B subunit. Exposure of C6 cells to butyrate induces an elevation of ganglioside G_M1 as measured by an increase in binding of iodinated cholera toxin and also results in an inhibition of DNA synthesis by the B subunit. The extent of inhibition of DNA synthesis correlated with the binding of B subunit and was independent of adenylate cyclase activation or increases in intracellular cAMP levels.