There are two types of facilitated diffusion carriers: Channel proteins transport only water or certain ions. They do so by forming a protein-lined passageway across the membrane. Many water molecules or ions can pass in single file through such channels at very fast rates.
What molecules use channel proteins?
Facilitated diffusion therefore allows polar and charged molecules, such as carbohydrates, amino acids, nucleosides, and ions, to cross the plasma membrane. Two classes of proteins that mediate facilitated diffusion are generally distinguished: carrier proteins and channel proteins.
What is a gated channel protein?
Ligand-gated ion channels (LICs, LGIC), also commonly referred as ionotropic receptors, are a group of transmembrane ion-channel proteins which open to allow ions such as Na+, K+, Ca2+, and/or Cl− to pass through the membrane in response to the binding of a chemical messenger (i.e. a ligand), such as a neurotransmitter