Many transmembrane proteins serve as routes through which hydrophilic solutes can cross the cell membrane. With reference to the relevant levels of protein structure, describe two different ways in which the structures of transmembrane proteins can facilitate this function.

Transmembrane proteins are the type of protein that are permanently attached to the cell membrane which serves as routes through which hydrophilic solute can cross the cell membrane. In order to allow specific molecules to move through the membrane, they would have to undergo significant changes. According to their structure, there are two types of transmembrane proteins and they includes:

-alpha- helical and

- beta-barrel proteins.

With reference to relevant levels of protein structure the two different ways in which the transmembrane proteins can facilitate transport of hydrophilic solutes across cell membrane includes:

1.) As Channel proteins: The transmembrane proteins which are involved in facilitated transport functions as channels for the solute. These channels are specific for the solute that is being transported. They have hydrophilic domains exposed to the intracellular and extracellular fluids; and a hydrophilic channel through their cone that provides a hydrated opening through the membrane layers. They are either open at all times or they are gated. For example, in some tissue like that of kidney, sodium and chloride ions pass freely through open channels; while in some others, like nerve and muscle, a gate must be opened to allow passage.

2.) As carrier proteins: the transmembrane proteins which are involved in facilitated transport can equally function as a carrier protein where it binds to a solute and in doing so, triggers a change of its own shape moving the bound molecules from outside of the cell to its interior: depending on the gradient, the molecules may move in the opposite direction. I hope this helps, thanks.