Final answer:
Trimeric G-proteins such as Gq or G12/13 have no effect on adenylate cyclase activity, as they are involved in different signaling pathways that do not utilize cAMP as a secondary messenger.
Step-by-step explanation:
The trimeric G-proteins that have no effect on adenylate cyclase activity are typically other classes of G-proteins that do not interact with adenylate cyclase, such as Gq or G12/13 proteins. The G-proteins are classified based on their effects on adenylate cyclase; Gs stimulates and Gi inhibits. The Gq class of G-proteins activates phospholipase C, leading to the production of inositol triphosphate (IP3) and diacylglycerol (DAG), not cAMP. G12/13 class is involved in regulating the Rho family of GTPases, which act on the actin cytoskeleton. Therefore, these G-proteins do not use adenylate cyclase or cAMP as part of their signaling mechanisms.
Adenylate cyclase catalyzes the conversion of ATP to cAMP, which then activates protein kinases like PKA resulting in a cascade of phosphorylation events that mediate cellular responses. Specificity in signaling is partly achieved because different G-proteins activate different effector enzymes and thus generate different second messengers leading to distinct cellular outcomes.