Robert J. Lefkowitz

Effect of pertussis toxin on α2-adrenoceptors: decreased formation of the high-affinity state for agonists

Administration of pertussis toxin to hamsters abolishes the α2‐adrenergic inhibition of adenylate cyclase in their adipocytes. The toxin did not modify the number of adipocyte α2‐adrenoceptors or their affinity for antagonists. In contrast, the affinity for agonists was significantly diminished in adipocyte membranes obtained from pertussis toxin‐treated hamsters as compared to the controls. This decrease in affinity was due to a significant diminution in the proportion of sites displaying the high‐affinity state for agonists. It is concluded that pertussis toxin induces a shift in the proportion of sites in high‐ and low‐affinity states for agonists towards the low‐affinity conformation.