Question

Which of the following is not a transport protein?

• A. Sodium-potassium pump
• B. Mechano-Sensitive ion Channels
• C. The sodium-calcium exchanger
• D. Lactose permease

Hint:

• Transport proteins include:
  • Pumps (ATPases) Use ATP for active transport (e.g., Na\(^+\)/K\(^+\) pump).
  • Carriers/Transporters (Permeases, Exchangers) Bind solute and undergo conformational changes (e.g., lactose permease, Na\(^+\)/Ca\(^{2+}\) exchanger). Can be uniport, symport, antiport; passive (facilitated diffusion) or active (secondary active transport).
  • Channels Form pores for passage of ions or water (e.g., ion channels, aquaporins). Can be gated (voltage-gated, ligand-gated, mechano-sensitive).
• All listed options are involved in the transport of substances across membranes. The question might be distinguishing based on primary functional classification.

Answer 1

The Correct Option is B

In biotechnology, understanding transport proteins is crucial. Transport proteins are responsible for moving substances across cellular membranes. Let's analyze each option to identify which one is not a transport protein:

• Sodium-potassium pump: This is a well-known transport protein that pumps sodium ions out of and potassium ions into cells, using ATP as energy.
• Mechano-Sensitive ion Channels: These are ion channels that open or close in response to mechanical forces, like pressure or tension, and do not actively transport substances across membranes. Rather, they regulate the flow of ions based on mechanical stimuli.
• The sodium-calcium exchanger: This is a transport protein that exchanges sodium ions for calcium ions across cellular membranes, maintaining ionic balance.
• Lactose permease: A transport protein that helps in the uptake of lactose into cells by utilizing a proton gradient.

Based on the descriptions above, the option that is not a transport protein is the Mechano-Sensitive ion Channels, as they serve different functions predominantly related to channeling rather than transporting substances actively.