Distinct N-terminal regulatory domains of Ca(2+)/H(+) antiporters

Plant Physiol. 2002 Oct;130(2):1054-62. doi: 10.1104/pp.008193.


The regulation of intracellular Ca(2+) levels is achieved in part by high-capacity vacuolar Ca(2+)/H(+) antiporters. An N-terminal regulatory region (NRR) on the Arabidopsis Ca(2+)/H(+) antiporter CAX1 (cation exchanger 1) has been shown previously to regulate Ca(2+) transport by a mechanism of N-terminal auto-inhibition. Here, we examine the regulation of other CAX transporters, both within Arabidopsis and from another plant, mung bean (Vigna radiata), to ascertain if this mechanism is commonly used among Ca(2+)/H(+) antiporters. Biochemical analysis of mung bean VCAX1 expressed in yeast (Saccharomyces cerevisiae) showed that N-terminal truncated VCAX1 had approximately 70% greater antiport activity compared with full-length VCAX1. A synthetic peptide corresponding to the NRR of CAX1, which can strongly inhibit Ca(2+) transport by CAX1, could not dramatically inhibit Ca(2+) transport by truncated VCAX1. The N terminus of Arabidopsis CAX3 was also shown to contain an NRR. Additions of either the CAX3 or VCAX1 regulatory regions to the N terminus of an N-terminal truncated CAX1 failed to inhibit CAX1 activity. When fused to N-terminal truncated CAX1, both the CAX3 and VCAX1 regulatory regions could only auto-inhibit CAX1 after mutagenesis of specific amino acids within this NRR region. These findings demonstrate that N-terminal regulation is present in other plant CAX transporters, and suggest distinct regulatory features among these transporters.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Antiporters / genetics
  • Antiporters / metabolism*
  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Biological Transport / drug effects
  • Calcium / metabolism*
  • Calcium / pharmacology
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism*
  • Cation Transport Proteins*
  • Cloning, Molecular
  • Fabaceae / genetics
  • Fabaceae / metabolism
  • Gene Expression Regulation, Plant
  • Histidine / pharmacology
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Mutation
  • Nitrogen / metabolism*
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism*
  • Saccharomyces cerevisiae / genetics
  • Sequence Homology, Amino Acid
  • Vacuoles / metabolism


  • Antiporters
  • Calcium-Binding Proteins
  • Cation Transport Proteins
  • Peptide Fragments
  • calcium-hydrogen antiporters
  • Histidine
  • Nitrogen
  • Calcium