it is now widely believed that the main rate-limiting step in the sodium-potassium pump ( na , k-atpase ) cycle is a conformational change between two forms of the dephosphoenzyme ( e2 and e1 ) and that this change releases to the cell interior potassium ions occluded within the e2 form .
C0001479
sodium-potassium pump
C0001473
atpase