Regulation of CAX1, an Arabidopsis Ca(2+)/H+ antiporter. Identification of an N-terminal autoinhibitory domain

Plant Physiol. 2001 Nov;127(3):1020-9.


Regulation of Ca(2+) transport determines the duration of a Ca(2+) signal, and hence, the nature of the biological response. Ca(2+)/H+ antiporters such as CAX1 (cation exchanger 1), play a key role in determining cytosolic Ca(2+) levels. Analysis of a full-length CAX1 clone suggested that the CAX1 open reading frame contains an additional 36 amino acids at the N terminus that were not found in the original clone identified by suppression of yeast (Saccharomyces cerevisiae) vacuolar Ca(2+) transport mutants. The long CAX1 (lCAX1) could not suppress the yeast Ca(2+) transport defects despite localization to the yeast vacuole. Calmodulin could not stimulate lCAX1 Ca(2+)/H+ transport in yeast; however, minor alterations in the 36-amino acid region restored Ca(2+)/H+ transport. Sequence analysis suggests that a 36-amino acid N-terminal regulatory domain may be present in all Arabidopsis CAX-like genes. Together, these results suggest a structural feature involved in regulation of Ca(2+)/H+ antiport.

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*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Calcium / metabolism*
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism*
  • Cation Transport Proteins*
  • Chromosome Mapping
  • Cytosol / metabolism
  • Hydrogen / metabolism*
  • Hydrogen-Ion Concentration
  • Ion Transport
  • Molecular Sequence Data
  • Protein Structure, Tertiary
  • Saccharomyces cerevisiae / metabolism
  • Sequence Homology, Amino Acid
  • Signal Transduction
  • Vacuoles / metabolism


  • Antiporters
  • Arabidopsis Proteins
  • Calcium-Binding Proteins
  • Cation Transport Proteins
  • calcium-hydrogen antiporters
  • Hydrogen
  • Calcium