Protein Phylogenetic Analysis of Ca2+/cation Antiporters and Insights into their Evolution in Plants

Cation transport is a critical process in all organisms and is essential for mineral nutrition, ion stress tolerance, and signal transduction. Transporters that are members of the Ca(2+)/cation antiporter (CaCA) superfamily are involved in the transport of Ca(2+) and/or other cations using the counter exchange of another ion such as H(+) or Na(+). The CaCA superfamily has been previously divided into five transporter families: the YRBG, Na(+)/Ca(2+) exchanger (NCX), Na(+)/Ca(2+), K(+) exchanger (NCKX), H(+)/cation exchanger (CAX), and cation/Ca(2+) exchanger (CCX) families, which include the well-characterized NCX and CAX transporters. To examine the evolution of CaCA transporters within higher plants and the…