Preventing the uncontrolled leakage of water-soluble substances by forming selective hydrophilic channels across the lipid bilayer.

Regulating membrane fluidity by preventing phospholipid tails from packing too tightly at low temperatures and stabilizing them at high temperatures.

Binding to hydrophilic peptide hormones to initiate intracellular secondary messenger signaling cascades.

Synthesizing and folding polypeptide chains on the extracellular surface of the lipid bilayer.