Neuropeptide Y inhibits pertussis toxin-catalyzed ADP-ribosylation in bovine adrenal chromaffin cell membranes.

Evidence is presented that the neuropeptide Y receptor is directly coupled to an inhibitory G protein existing in cultured bovine adrenal chromaffin cell membranes. Pertussis toxin catalyzes the [32P]ADP-ribosylation of a 41 kDa plasma membrane protein. 5'-Guanylylimidodiphosphate inhibited the [32P]ADP labelling of this protein in a dose-dependent manner whereas GTP had no effect. Preincubation of the plasma membranes with high concentrations of neuropeptide Y followed by a brief exposure to a low concentration of 5'-guanylylimidodiphosphate significantly inhibited ADP-ribosylation beyond that observed with 5'-guanylylimidodiphosphate alone. These results suggest that the neuropeptide Y receptor in bovine adrenal chromaffin cells is directly coupled to a 41 kDa PTX substrate (presumably the alpha subunit of an inhibitory G protein).