Nonenzymatic augmentation of lactate transport via monocarboxylate transporter isoform 4 by carbonic anhydrase II

J Membr Biol. 2010 Apr;234(2):125-35. doi: 10.1007/s00232-010-9240-y. Epub 2010 Mar 19.


Monocarboxylate transporters (MCTs) are carriers of high-energy metabolites like lactate and pyruvate, and different MCT isoforms are expressed in a wide range of cells and tissues. Transport activity of MCT isoform 1 (MCT1), heterologously expressed in Xenopus oocytes, has previously been shown to be supported by carbonic anhydrase II (CAII) in a noncatalytic manner. In the present study, we investigated possible interactions of CAII with MCT4, expressed in Xenopus oocytes. MCT4 transport activity is enhanced both by injected and by coexpressed CAII, similar to MCT1, with the highest augmentation at low extracellular pH and low lactate concentrations. CAII-induced augmentation in MCT4 transport activity is independent from the enzyme's catalytic function, as shown by application of the CA inhibitor ethoxyzolamide and by coexpression of MCT4 with the catalytically inactive mutant CAII-V143Y.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carbonic Anhydrase II / metabolism*
  • Carbonic Anhydrase Inhibitors / pharmacology
  • Catalysis
  • Ethoxzolamide / pharmacology
  • Humans
  • Hydrogen-Ion Concentration
  • Lactic Acid / metabolism*
  • Monocarboxylic Acid Transporters / metabolism*
  • Muscle Proteins / metabolism*
  • Oocytes / metabolism
  • Rats
  • Xenopus laevis


  • Carbonic Anhydrase Inhibitors
  • Monocarboxylic Acid Transporters
  • Muscle Proteins
  • Slc16a3 protein, rat
  • Lactic Acid
  • Carbonic Anhydrase II
  • Ethoxzolamide