High-affinity binding of forskolin to rat brain membranes.

High-affinity forskolin binding sites in brain membranes have been identified that have structure-activity characteristics compatible with forskolin's site of action at the adenylate cyclase enzyme. It is proposed that these high-affinity binding sites are associated with an activated complex of the catalytic protein and the alpha s subunit. Quantitation of high-affinity forskolin binding sites may provide a direct measure of the amount of adenylate cyclase that has the potential to be regulated by stimulatory hormones and the Ns subunit.