Functional asymmetry of bidirectional Ca2+-movements in an archaeal sodium-calcium exchanger (NCX_Mj).

•The turnover rates of the ion-exchange cycle are 103–104 times slower in NCX_Mj than in mammalian NCX.•Asymmetric Ca2+ movements represent a basic mechanism that diversifies Km values at opposite sides.•Eukaryotic and prokaryotic NCX proteins share a common mechanism for asymmetric Ca2+ movements.•Regulatory domains of mammalian NCX secondarily modulate the asymmetric Ca2+ movements.