Submitted to: Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2000
Publication Date: 12/17/2000
Citation: 257:291-298, 2000 Interpretive Summary: Plants contain many different transporters to move nutrients into cellular compartments. We have isolated and characterized several new transporters which are similar to previously characterized transporters; however, these new transporters do not function like the transporters we have previously characterized. This study suggests that although transporters are similar, they have different functions within the plant. This study suggests that many transporters within a plant do not have similar functions.
Technical Abstract: Transporter-mediated Ca2+ efflux from the cytoplasm is an important component of plant signal transduction. To elucidate the diversity and role of Ca2+/H+ in controlling plant cytosolic Ca2+ concentrations, homologs of CAX (for calcium exchanger) genes were cloned from Zea mays and Arabidopsis thaliana cDNA libraries. The A. thaliana homolog of CAX (AtHCX1) is 77% identical to CAX1 while the Z. Mays homolog of CAX (ZmHCX1) is 64% identical to CAX1 in amino acid sequence. AtHCX1 transcripts appeared to be expressed in all tissues, and levels of AtHCX1 RNA increased after Ca2+ or Na+ treatment. When expressed in yeast mutants defective in vacuolar Ca2+ uptake, ZmHCX1 and AtHCX1 failed to suppress the Ca2+ sensitivity of these strains. These results imply that CAX-like genes may have functions in plant ion homeostasis that differ from those of previously characterized CAX genes.