Foetal calf serum enhances cholera toxin-catalysed ADP-ribosylation of the pertussis toxin-sensitive guanine nucleotide binding protein, G i2, in rat glioma C6BU1 cells

Abstract

The major G-protein of rat glioma C6BU1 cells corresponds immunologically to G i2. In the absence of guanine nucleotides, this protein is shown to be a substrate for ADP-ribosylation catalysed by both cholera and pertussis toxins. Under these conditions, a receptor for a growth factor, which has previously been shown to be activated by foetal calf serum, modulated the effects of both cholera and pertussis toxins on the G-protein. These ligand-mediated alterations of cholera and pertussis toxin-catalysed ADP ribosylation demonstrated that, in this system, the growth factor receptor interacts functionally with G i2.