What are proteins embedded in the plasma membrane that facilitate movement of substances in and out of cells called?

Proteins embedded in the plasma membrane that facilitate the movement of substances in and out of cells are known as carrier proteins. These proteins serve a crucial role in selectively transporting molecules across the membrane, typically involving conformational changes that allow the binding and release of specific substances. Carrier proteins are essential for the active and passive transport of various molecules, such as glucose and amino acids, and they often work by binding to the substance they need to transport and subsequently changing shape to shuttle it across the membrane.

In contrast, channel proteins also assist in the movement of substances but do so by forming openings or pores that allow specific ions or water molecules to pass through freely. Receptor proteins are involved in signaling processes by binding to specific signaling molecules, while structural proteins provide support and shape to the cell rather than facilitating the transport of substances. Each of these protein types plays distinct roles within the plasma membrane, but carrier proteins are uniquely responsible for the active and selective transport of materials across the cell membrane.