SEARCH Articles Figures Tables E -E2 reaction cycle of H,K-ATPase, accounting for the transport of two H and two K ions per molecule of hydrolysed ATP. The ATPase reaction proceeds from 2H E, ATP through 2H E -P and 2H E2-P to 2K E. Details of the reaction cycle are described in the text. [Publishers Imprint] [Publishers Imprint] [Publishers Imprint] [Publishers Imprint] [Publishers Imprint] [Publishers Imprint] [Publishers Imprint] [Publishers Imprint] [Publishers Imprint]