The relationship between pertussis-toxin-induced ADP-ribosylation of a plasma-membrane protein and reversal of muscarinic inhibition of prolactin secretion in GH3 cells.

Pertussis toxin (PT) caused the ADP-ribosylation of a Mr-41 000 protein in GH3-cell plasma-membrane preparations. This effect, and muscarinic inhibition of prolactin release, were reversed at similar rates by pretreatment of intact cells with PT. These results suggest that the Mr-41 000 protein is modified in intact GH3 cells, and that this protein (a component of the putative Ni unit of adenylate cyclase) is involved in the expression of muscarinic inhibition.