“In contrast, addition of forskolin during proteolysis with chymotrypsin prevented the time- and concentration-dependent decline in forskolin stimulation observed with chymotrypsin.”
“Proteolysis with chymotrypsin led to a concentration- and time-dependent increase in activation of adenylate cyclase by isoproterenol + guanine nucleotides, and fluoride, and to a decrease in activation by forskolin.”
“Since forskolin is thought to act directly on the catalytic unit of adenylate cyclase, and since forskolin can protect against the effect of proteolysis with chymotrypsin , the site involved may be on the catalytic unit itself.”