Which of the following is an example of an ion-channel receptor?

• A. Nicotinic acetylcholine receptor
• B. Insulin receptor
• C. G protein-coupled receptor
• D. Epidermal growth factor receptor

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the concept of ion-channel receptors. Ion-channel receptors are a type of membrane protein that allows ions to pass through the membrane in response to a ligand binding. These receptors are also known as ligand-gated ion channels.
2. Step 2: Review the function of the nicotinic acetylcholine receptor. This receptor is a well-known example of an ion-channel receptor. When acetylcholine binds to it, the receptor opens a channel that allows ions such as Na⁺ and K⁺ to flow across the membrane.
3. Step 3: Examine the insulin receptor. The insulin receptor is a receptor tyrosine kinase, not an ion-channel receptor. It functions by activating intracellular signaling pathways upon insulin binding.
4. Step 4: Analyze the G protein-coupled receptor (GPCR). GPCRs are a different class of receptors that activate intracellular signaling cascades through G proteins, but they do not form ion channels.
5. Step 5: Consider the epidermal growth factor receptor (EGFR). EGFR is another receptor tyrosine kinase, which is involved in cell signaling and does not function as an ion-channel receptor. Based on this analysis, the nicotinic acetylcholine receptor is the correct example of an ion-channel receptor.