The Na+/K+ ATPase of the plasma membrane catalyzes the exchange of Na+ and K+ io
ID: 770440 • Letter: T
Question
The Na+/K+ ATPase of the plasma membrane catalyzes the exchange of Na+ and K+ ions across the membrane. From the following list of statements, select all that correctly describe features or properties of this transport system. Pumps Na+ ions out of the cell. Pumps Na+ ions into the cell. Pumps K+ ions out of the cell. Pumps K+ ions into the cell. Exchanges 3 Na+ ions for 2 K+ ions. Exchanges 3 K+ ions for 2 Na+ ions. Creates a membrane potential that is negative on the inside. Creates a membrane potential that is positive on the inside. The transport protein becomes phosphorylated by ATP during the transport cycle. The transport protein becomes adenylated by ATP during the transport cycle.Explanation / Answer
correct statements: 1,4,5,7,9 Mechanism: The pump, while binding ATP, binds 3 intracellular Na+ ions.[1] ATP is hydrolyzed, leading to phosphorylation of the pump at a highly conserved aspartate residue and subsequent release of ADP. A conformational change in the pump exposes the Na+ ions to the outside. The phosphorylated form of the pump has a low affinity for Na+ ions, so they are released. The pump binds 2 extracellular K+ ions. This causes the dephosphorylation of the pump, reverting it to its previous conformational state, transporting the K+ ions into the cell. The unphosphorylated form of the pump has a higher affinity for Na+ ions than K+ ions, so the two bound K+ ions are released. ATP binds, and the process starts again.