Question

G-protein coupled receptors are multi pass membrane proteins and span

• A. Only one time in the plasma membrane
• B. Three times in the plasma membrane
• C. Five times in the plasma membrane
• D. Seven times in the plasma membrane

Hint:

GPCR Structure: 7 Transmembrane $\alpha$-helices (Serpentine receptor) coupled to heterotrimeric G-proteins ($G_s, G_i, G_q$).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
G-Protein Coupled Receptors (GPCRs 7TM receptors) share a conserved structural architecture of seven hydrophobic transmembrane $lpha$-helices.

Step 2: Detailed Explanation:
G-Protein Coupled Receptors (GPCRs Serpentine Receptors 7TM Receptors) represent the largest eukaryotic superfamily of cell surface receptors:
- They consist of a single polypeptide chain that winds back and forth across the lipid bilayer seven times, forming seven hydrophobic transmembrane $\alpha$-helices (TM1 to TM7).
- They have an extracellular N-terminus (ligand binding) and an intracellular C-terminus (interacts with heterotrimeric $G_{\alpha\beta\gamma}$ proteins).

Step 3: Final Answer:
Hence, GPCRs span Seven times in the plasma membrane, matching option (D).