Properties and molecular cloning of Ca2+/H+ antiporter in the vacuolar membrane of mung bean

Eur J Biochem. 1999 Jun;262(2):417-25. doi: 10.1046/j.1432-1327.1999.00377.x.


Kinetic and molecular properties of the Ca2+/H+ antiporter in the vacuolar membrane of mung bean hypocotyls were examined and compared with Ca2+-ATPase. Ca2+ transport activities of both transporters were assayed separately by the filtration method using vacuolar membrane vesicles and 45Ca2+. Ca2+ uptake in the presence of ATP and bafilomycin A1, namely Ca2+-ATPase, showed a relatively low Vmax (6 protein) and a low Km for Ca2+. The Ca2+/H+ antiporter activity driven by H+-pyrophosphatase showed a high Vmax (25 and a relatively high Km for Ca2+. The cDNA for mung bean Ca2+/H+ antiporter (VCAX1) codes for a 444 amino-acid polypeptide. Two peptide-specific antibodies of the antiporter clearly reacted with a 42-kDa protein from vacuolar membranes and a cell lysate from a Escherichia coli transformant in which VCAX1 was expressed. These observations directly demonstrate that a low-affinity, high-capacity Ca2+/H+ antiporter and a high-affinity Ca2+-ATPase coexist in the vacuolar membrane. It is likely that the Ca2+/H+ antiporter removes excess Ca2+ in the cytosol to lower the Ca2+ concentration to micromolar levels after stimuli have increased the cytosolic Ca2+ level, the Ca2+-ATPase then acts to lower the cytosolic Ca2+ level further.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antiporters / chemistry*
  • Antiporters / genetics
  • Base Sequence
  • Calcium-Binding Proteins / chemistry*
  • Calcium-Binding Proteins / genetics
  • Calcium-Transporting ATPases / metabolism
  • Cation Transport Proteins*
  • Cloning, Molecular
  • DNA, Complementary
  • Fabaceae / metabolism*
  • Kinetics
  • Molecular Sequence Data
  • Plants, Medicinal*
  • Sequence Homology, Amino Acid


  • Antiporters
  • Calcium-Binding Proteins
  • Cation Transport Proteins
  • DNA, Complementary
  • calcium-hydrogen antiporters
  • Calcium-Transporting ATPases

Associated data

  • GENBANK/AB012932