How do cells relocate transmembrane proteins from one side of the cell to the other? Is it possible?

Question

Is there a process by which cells can relocate proteins residing on the cell membrane in areas of low demand to that of a high demand location somewhere else in on the cell? What's that process called?Through protein catabolism, cells can break down the proteins into their individual amino acids and then reuse these resources to build new proteins in needed locations. This process seems inefficient if the cell simply needs to move a transmembrane protein (for example integrin or cadherin) from one side of the cell to the other. I hope the question is clear. I haven't taken a biology course since early high school (8 years ago) so if there's something i need to clarify let me know!

Answer 1

You bring up an interesting point! After all: If you already have the protein you need, why expend energy breaking down and building new ones? Let's address your questions systematically:

-There are transporter proteins that carry neurotransmitters, proteins, and steroid hormones across the cell membrane. Since proteins are bulky macromolecules with complex structures, they need help crossing lipid bilayer that constitutes cell membranes. These are usually "ATPases", or proteins that use ATP hydrolysis to help drive the reaction.

-Given that proteins are such bulky, complex, 3D macromolecular machines, it actually requires a fair amount of energy (or ATP) to transport them anywhere. Since amino acids are much smaller and the fact that some are aqueous, they require less energy to transport. Additionally, proteins are not synthesized at sites that require them. They are synthesized in the ER and ribosomes. They obtain a localization tag in the Golgi that shuttles them to their respective locations through a complex system of chaperone proteins and vesicles.

Hope this helps!

Sam

Answer 2

A transmembrane protein spans the entire plasma membrane. There is no need to transport them from one side to the other. If they need to move for whatever reason they can move sideways in the membrane and could eventually end up on the other side of the cell. Their movement is still going to be driven by chemical forces. If you have any further questions or would like to schedule a tutoring session please feel free to send me a message. I am happy to help!