Disease relevance of CAX4

• CAX4 driven by the CaMV 35S and FS3 [figwort mosaic virus (FMV)] promoters increased the magnitude and initial rate of Cd(2+)/H(+) exchange in root-tonoplast vesicles [1].

High impact information on CAX4

• We show that these mutants exhibit a 50% reduction in tonoplast Ca(2+)/H(+) antiport activity, a 40% reduction in tonoplast V-type H(+)-translocating ATPase activity, a 36% increase in tonoplast Ca(2+)-ATPase activity, and increased expression of the putative vacuolar Ca(2+)/H(+) antiporters CAX3 and CAX4 [2].
• We then compared the phenotypes of sCAX1- and CAX4-expressing tomato lines [3].
• Several modifications to CAX4 allowed the protein to transport Ca(2+) [4].
• To understand the diversity and role of H(+)/cation transporters in controlling plant ion levels, another homolog of the CAX genes, CAX4, was cloned from an Arabidopsis cDNA library [4].
• CAX4 transcripts appeared to be expressed at low levels in all tissues and levels of CAX4 RNA increased after Mn(2+), Na(+), and Ni(2+) treatment [4].

Biological context of CAX4

• Ion selectivity of transport in root-tonoplast vesicles isolated from FS3::CAX4-expressing plant lines having a range of gene expression was Cd(2+)>Zn(2+)>>Ca(2+)>>Mn(2+) and the ratios of maximal Cd(2+) (and Zn(2+)) versus maximal Ca(2+) and Mn(2+) transport were correlated with the levels of CAX4 expression [1].

Associations of CAX4 with chemical compounds

• Root Cd accumulation in high CAX4 and CAX2 expressing lines was increased in seedlings grown with 0.02 muM Cd [1].

References