Transport proteins, also known as transmembrane proteins, are membrane proteins that aid in the facilitated diffusion or active transport of ions across the hydrophobic lipid bilayer.
Such proteins include channel proteins, carrier proteins, sodium-potassium pumps, GLUT1, proton pump, calcium ATPase, and others.
Within the plasma membrane, there are two primary types of transport proteins, each of which aids in the passage of water-loving molecules across the membrane.
A channel protein acts as a passageway through the cell's membrane.