What is the primary function of proteins embedded in the lipid bilayer?

Proteins embedded in the lipid bilayer play a critical role in the functionality of cellular membranes. Their primary function is to transport molecules across the membrane. These proteins can act as pumps, channels, or carriers, facilitating the movement of ions, nutrients, and other substances into and out of the cell. This transport is essential for maintaining the cell's internal environment and is integral to processes such as cell signaling, nutrient uptake, and waste removal.

Additionally, these membrane proteins can also serve other functions, including acting as receptors for signaling molecules, enzymes for catalyzing reactions, and structural components that help maintain the cell's shape and stability. This multifaceted role highlights their importance in cellular operations beyond merely being a physical barrier to the external environment, emphasizing why this choice is the most accurate in describing their primary function.