What is the primary role of carrier proteins in cellular membranes?

The primary role of carrier proteins in cellular membranes is the transport of substances across membranes. These proteins facilitate the movement of molecules that are unable to pass through the lipid bilayer of the membrane directly due to their size, charge, or polarity. Carrier proteins bind specifically to the substances they transport, undergoing conformational changes to move these molecules from one side of the membrane to the other. This process can occur through passive transport, where molecules move along their concentration gradient, or active transport, where energy is used to move molecules against their gradient.

Understanding this function is essential, as it highlights the critical role of carrier proteins in various biological processes, including nutrient uptake, waste removal, and signaling pathways.