Which of the following is not a type of cell surface receptors?

• A. Ion Channel Receptors
• B. G-Protein Coupled Receptors
• C. Signal Coupled Receptors
• D. Enzyme Coupled Receptors

Answer: (C)

Verified step by step guidance

1. Understand the role of cell surface receptors: Cell surface receptors are proteins located on the cell membrane that receive and transmit signals from the extracellular environment to the inside of the cell.
2. Identify the common types of cell surface receptors: The main types include Ion Channel Receptors, G-Protein Coupled Receptors, and Enzyme Coupled Receptors.
3. Ion Channel Receptors: These receptors open or close ion channels in response to ligand binding, allowing ions to pass through the membrane.
4. G-Protein Coupled Receptors: These receptors activate G-proteins in response to ligand binding, which then trigger various intracellular signaling pathways.
5. Enzyme Coupled Receptors: These receptors have enzymatic activity or are associated with enzymes that are activated upon ligand binding. Recognize that 'Signal Coupled Receptors' is not a standard category of cell surface receptors, indicating it is not a type of cell surface receptor.