Two additional type IIA Ca2+-ATPases are expressed in Arabidopsis thaliana: evidence that type IIA sub-groups exist

High affinity Ca2+-ATPases play a central role in calcium homeostasis by ca talysing the active efflux of calcium from the cytoplasm. This study report s the identification of two additional type IIA (SERCA-type) Ca2+-ATPases f rom Arabidopsis (AtECA2 and AtECA3), and describes the detailed sequence an alysis of these genes in comparison with AtECA1 and other plant and animal Ca2+-ATPases. Southern analysis suggests that each of these genes is presen t as a single copy and also that there may be a small family of moderately related genes that encode type IIA Ca2+-ATPases in Arabidopsis. Evidence is also provided from RT-PCR that these genes are expressed in Arabidopsis. H ydropathy analysis predicts that the topology of the Arabidopsis type IIA p roteins is similar to the animal SERCA proteins. Sequence and phylogenetic analyses suggest that the type IIA Ca2+-ATPases can be further divided into sub-groups. (C) 1999 Elsevier Science B.V. All rights reserved.