A<unk>  is a protein that spans the entire biological membrane.<unk> s aggregate and precipitate in water. They require detergents or nonpolar solvents for extraction, although some of them (beta-barrels) can be also extracted using denaturing agents.
Transmembrane protein
Membrane transport protein
Glycoprotein
Protein precursor
Ion channel
Membrane fusion protein
Diatomic molecule
Ion transporter