Sodium potassium pump

1

three cytoplasmic Na+ bind to pump protein

2

Na+ binding promotes hydrolysis of ATP. The energy released during this reaction phosphorylates the pump.

3

Phosphorylation causes the pump to change shape, expelling Na+ to the outside

4

2 extracellular K+ bind to pump

5

K+ binding triggers release of the phosphate. The dephosphorylated pump resumes its original conformation

6

The pump protein binds ATP and releases K+ to the inside, and Na+ sites are ready to bind Na+ again. The cycle repeats