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Characterization of CXIP4, a novel Arabidopsis protein that activates the H + /Ca 2+ antiporter, CAX1
Author(s) -
Cheng Ning-Hui,
Liu Jian-Zhong,
Nelson Richard S,
Hirschi Kendal D
Publication year - 2004
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(04)00036-5
Subject(s) - arabidopsis , antiporter , yeast , fusion protein , saccharomyces cerevisiae , biology , green fluorescent protein , mutant , transporter , biochemistry , transport protein , arabidopsis thaliana , microbiology and biotechnology , gene , recombinant dna , membrane
Precise regulation of calcium transporters is essential for modulating the Ca 2+ signaling network that is involved in the growth and adaptation of all organisms. The Arabidopsis H + /Ca 2+ antiporter, CAX1, is a high capacity and low affinity Ca 2+ transporter and several CAX1‐like transporters are found in Arabidopsis . When heterologously expressed in yeast, CAX1 is unable to suppress the Ca 2+ hypersensitivity of yeast vacuolar Ca 2+ transporter mutants due to an N‐terminal autoinhibition mechanism that prevents Ca 2+ transport. Using a yeast screen, we have identified A nteracting rotein 4 (CXIP4) that activated full‐length CAX1, but not full‐length CAX2, CAX3 or CAX4. CXIP4 encodes a novel plant protein with no bacterial, fungal, animal, or mammalian homologs. Expression of a GFP‐CXIP4 fusion in yeast and plant cells suggests that CXIP4 is targeted predominantly to the nucleus. Using a yeast growth assay, CXIP4 activated a chimeric CAX construct that contained specific portions of the N‐terminus of CAX1. Together with other recent studies, these results suggest that CAX1 is regulated by several signaling molecules that converge on the N‐terminus of CAX1 to regulate H + /Ca 2+ antiport.