What is the function of this membrane protein? A molecular view of the plasma membrane. There are two layers of phospholipids and two identical transmembrane proteins embedded in the phospholipid. The first protein has a gate that is closed and a site in the ECF where a ligand can bind. The second proteins has a ligand already bound to it and it's gate is open. What is the function of this membrane protein? a) to form the bilayer of the membrane b) linker protein c) receptor d)enzyme.