Which membrane protein is responsible for transporting sodium and potassium ions across the cell membrane?

Which membrane protein is responsible for transporting sodium and potassium ions across the cell membrane?

• A. Carrier Protein
• B. Channel Protein
• C. Enzymatic Proteins
• D. Receptor Protein

Answer: (A)

The main idea is how membranes move ions: some proteins form channels that allow ions to pass passively, while others bind ions and actively shuttle them across by changing shape. The sodium–potassium pump works by binding Na+ and K+ on one side of the membrane and using energy from ATP hydrolysis to drive a conformational change that moves those ions to the other side. This active, conformationally driven movement is the hallmark of a carrier protein that functions as a pump. While this protein is also an enzyme (it hydrolyzes ATP), its role in transporting ions across the membrane is best described by its carrier-like action—moving ions against their gradients rather than just forming a passive pore. Channel proteins would not require ATP and would pass ions through a pore, and receptor proteins don’t transport ions.

The main idea is how membranes move ions: some proteins form channels that allow ions to pass passively, while others bind ions and actively shuttle them across by changing shape. The sodium–potassium pump works by binding Na+ and K+ on one side of the membrane and using energy from ATP hydrolysis to drive a conformational change that moves those ions to the other side. This active, conformationally driven movement is the hallmark of a carrier protein that functions as a pump. While this protein is also an enzyme (it hydrolyzes ATP), its role in transporting ions across the membrane is best described by its carrier-like action—moving ions against their gradients rather than just forming a passive pore. Channel proteins would not require ATP and would pass ions through a pore, and receptor proteins don’t transport ions.