The sodium-potassium pump in animal cells requires cytoplasmic ATP to pump ions across the plasma membrane. When the proteins of the pump are first synthesized in the rough ER, what side of the ER membrane will the ATP binding site be on? A. It will be on the cytoplasmic side of the ER. B. It will be on the side facing the interior of the ER. C. It could be facing in either direction because the orientation of proteins is scrambled in the Golgi apparatus. D. It doesn't matter, because the pump Is not active in the ER. E. Not enough Information is provided to answer this question.

Answer: The correct answer is option A

It will be on the cytoplasmic side of the ER.

Explanation: Active transport is an energy requiring process, it involves the pumping of molecules and ions accross membranes against a concentration gradient.

The sodium-potassium is an active transport pump/system that exchanges sodium ion for potassium ion.

In the presence of cytoplasmic Adenosine Triphosphate, the proteins of the sodium-potassium pump are synthesized in the rough endoplasmic reticulum, the Adenosine Triphosphate binds to the cytoplasmic side of the endoplasmic reticulum moving sodium and potassium ion against large concentration gradients. The sodium-potassium pump moves two (2) potassium into the cell where potassium levels are high (intracellular) and pumps three (3) sodium out of the cell and into the extracellular fluid compartment.

A

Explanation:

The Endoplasmic reticulum is now responsible for pumping cytoplasmic ATP across the plasma membrane. the Proteins could be send to the Golgi apparatus for packaging and from there to the nucleus. The ER is responsible for synthesizing these proteins because of its proximity to the nucleus