When epinephrine binds to a(n) ________________ receptor, _______ is activated, causing an increase in the cellular concentration of ________________.

• A. Beta ; G_αi ; Inositol triphosphate.
• B. Alpha ; G_αq ; Inositol triphosphate.
• C. Beta ; G_αi ; Diacylglycerol.
• D. Alpha ; G_αs ; cAMP.
• E. Beta ; G_αq ; Diacylglycerol & Inositol triphosphate.

Answer: (B)

Verified step by step guidance

1. Identify the type of receptor that epinephrine binds to. Epinephrine can bind to different types of adrenergic receptors, such as alpha and beta receptors, which are part of the G protein-coupled receptor family.
2. Determine the specific G protein that is activated upon epinephrine binding. Different receptors activate different G proteins, such as Gαs, Gαi, or Gαq, each leading to distinct signaling pathways.
3. Understand the signaling pathway associated with the activated G protein. For example, Gαq activation typically leads to the activation of phospholipase C, which then catalyzes the formation of inositol triphosphate (IP3) and diacylglycerol (DAG).
4. Consider the cellular effects of the signaling molecules produced. IP3 increases intracellular calcium levels, while DAG activates protein kinase C, both contributing to various cellular responses.
5. Review the options provided and match the correct receptor type, G protein, and signaling molecules based on your understanding of the signaling pathways involved in epinephrine action.