ACCELERATED COMMUNICATION Activation of Type II Adenylate Cyclase by D2 and D4 but Not

The D2-like dopamine receptors couple to a variety of signal transduction pathways, including inhibition of adenylate cy-clase, mitogenesis, and activation of potassium channels. Al-though these effects are mediated via pertussis toxin-sensitive G proteins, Gi/o, it is likely that some of these effects are influenced by the release of G protein bg subunits. Type II adenylate cyclase (ACII) is highly regulated by multiple bio-chemical stimuli, including protein kinase C, forskolin, G protein a subunits, and G protein bg subunits. The ability of bg sub-units to activate this enzyme in the presence of activated as has been particularly well characterized. Although stimulation by bg subunits has been described as conditional on the presence of activated as, bg subunits also potentiate ACII activity after activation of protein kinase C. We created stable cell lines expressing ACII and the D2L receptor, the D3 receptor, or th