Characterization of CXIP4, a novel Arabidopsis protein that activates the H+/Ca2+ antiporter, CAX1

FEBS Letters

Hirschi, Kendal D²  Liu, Jian-Zhong¹  Cheng, Ning-Hui²  Nelson, Richard S¹ 

[1] Plant Biology Division, Samuel Roberts Noble Foundation, Inc., 2510 Sam Noble Parkway, Ardmore, OK 73402, USA;United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Baylor College of Medicine, 1100 Bates Street, Houston, TX 77030, USA

关键词: H+/Ca2+ antiporter;    Calcium signaling;    CAX1;    Activation;    Arabidopsis;    CAX;    cation exchanger;    sCAX;    deregulated CAX missing the N-terminal autoinhibitor;    YPD;    yeast extract/peptone/dextrose medium;    CXIP;    CAX interacting protein;   

DOI  :  10.1016/S0014-5793(04)00036-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Precise regulation of calcium transporters is essential for modulating the Ca²⁺ signaling network that is involved in the growth and adaptation of all organisms. The Arabidopsis H⁺/Ca²⁺ antiporter, CAX1, is a high capacity and low affinity Ca²⁺ transporter and several CAX1-like transporters are found in Arabidopsis. When heterologously expressed in yeast, CAX1 is unable to suppress the Ca²⁺ hypersensitivity of yeast vacuolar Ca²⁺ transporter mutants due to an N-terminal autoinhibition mechanism that prevents Ca²⁺ transport. Using a yeast screen, we have identified Anteracting 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⁺/Ca²⁺ antiport.

【 授权许可】

Unknown