Plant and animal type 2B Ca2+-ATPases: evidence for a common auto-inhibitory mechanism

Plant auto-inhibited Ca(2+)-ATPase 8 (ACA8) and animal plasma membrane Ca(2+)-ATPase 4b (PMCA4b) are representatives of plant and animal 2B P-type ATPases with a regulatory auto-inhibitory domain localized at the N- and C-terminus, respectively. To check whether the regulatory domain works independently of its terminal localization and if auto-inhibitory domains of different organisms are interchangeable, a mutant in which the N-terminus of ACA8 is repositioned at the C-terminus and chimeras in which PMCA4b C-terminus is fused to the N- or C-terminus of ACA8 were analysed in the yeast mutant K616 devoid of endogenous Ca(2+)-ATPases. Results show that the regulatory function of the terminal domain is independent from its position in ACA8 and that the regulatory domain belonging to PMCA4b is able to at least partially auto-inhibit ACA8.