Question

What sort of receptor is the muscarinic receptor?

• A. A G-protein coupled receptor.
• B. A kinase linked receptor.
• C. An intracellular receptor.
• D. An ion channel.

Answer 1

The Correct Option is A

Step 1: Understanding Muscarinic Receptors - Muscarinic receptors are cholinergic receptors that respond to the neurotransmitter acetylcholine (ACh). - These receptors belong to the G-protein coupled receptor (GPCR) family, which means they mediate signal transduction through intracellular second messengers.


Step 2: Evaluating the Given Options - (A) G-protein coupled receptor (GPCR) (Correct Answer): - Muscarinic receptors are metabotropic and mediate their effects via G-proteins (Gi or Gq). - They regulate second messengers such as cAMP and IP₃/DAG in various cellular processes.
- (B) Kinase-linked receptor: - These receptors are enzyme-linked (e.g., insulin receptors) and do not include muscarinic receptors.
- (C) Intracellular receptor: - These receptors, such as steroid hormone receptors, are located inside the cell and are not muscarinic receptors.
- (D) Ion channels: - Nicotinic receptors (not muscarinic) belong to the ligand-gated ion channel family.


Step 3: Selecting the Correct Answer - Since muscarinic receptors are G-protein coupled receptors (GPCRs), the correct choice is (A) A G-protein coupled receptor.