Question

Channel proteins present in the plasma membrane are

• A. Exclusively peripheral
• B. Exclusively integral
• C. Cytoplasmic
• D. Peripheral protein present in the cytosolic face

Hint:

Membrane Transport: All Channel proteins and Carrier pumps are Transmembrane Integral Membrane Proteins.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Membrane transport proteins span the hydrophobic core of the phospholipid bilayer as multi-pass transmembrane integral proteins.

Step 2: Detailed Explanation:
Channel proteins (such as aquaporins, voltage-gated $\text{Na}^+/\text{K}^+$ channels, and ionotropic ligand-gated channels) form hydrophilic aqueous pores through which specific solutes cross the biological membrane:
- To provide a continuous hydrophilic conduit across the entire hydrophobic hydrocarbon lipid core (thickness $\approx 3-4\text{ nm}$), channel proteins must span from the extracellular face to the cytosolic face via multiple amphipathic transmembrane $\alpha$-helices or $\beta$-barrels.
- Therefore, channel proteins are exclusively integral transmembrane proteins.

Step 3: Final Answer:
Therefore, channel proteins are Exclusively integral, matching option (B).