AUTHOR=Han Beibei , Tai Yuxin , Li Shuping , Shi Junmei , Wu Xueqing , Kakeshpour Tayebeh , Weng Jianfeng , Cheng Xianguo , Park Sunghun , Wu Qingyu TITLE=Redefining the N-Terminal Regulatory Region of the Ca2+/H+ Antiporter CAX1 in Tomato JOURNAL=Frontiers in Plant Science VOLUME=13 YEAR=2022 URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.938839 DOI=10.3389/fpls.2022.938839 ISSN=1664-462X ABSTRACT=
Calcium (Ca2+) is an essential plant nutrient, and Ca2+/H+ exchangers (CAXs) regulate Ca2+ partitioning between subcellular compartments. AtCAX1 activity is inhibited by its N-terminal regulatory region (NRR), which was initially defined as the sequence between the first two methionines. However, the accuracy of this NRR definition and the NRR regulatory mechanism remain unclear. Here, using tomato SlCAX1 as a model, we redefined the NRR of CAXs and demonstrated that our new definition is also applicable to Arabidopsis AtCAX1 and AtCAX3. The N-terminal-truncated SlCAX1 (SlCAX1Δ39) but not the full-length SlCAX1 was active in yeast, similar to Arabidopsis AtCAX1. Characterization of