MilliporeSigma
  • Home
  • Search Results
  • Intracellular and extracellular carbonic anhydrases cooperate non-enzymatically to enhance activity of monocarboxylate transporters.

Intracellular and extracellular carbonic anhydrases cooperate non-enzymatically to enhance activity of monocarboxylate transporters.

The Journal of biological chemistry (2013-12-18)
Michael Klier, Fabian T Andes, Joachim W Deitmer, Holger M Becker
ABSTRACT

Proton-coupled monocarboxylate transporters (MCTs) are carriers of high-energy metabolites such as lactate, pyruvate, and ketone bodies and are expressed in most tissues. It has previously been shown that transport activity of MCT1 and MCT4 is enhanced by the cytosolic carbonic anhydrase II (CAII) independent of its catalytic activity. We have now studied the influence of the extracellular, membrane-bound CAIV on transport activity of MCT1/4, heterologously expressed in Xenopus oocytes. Coexpression of CAIV with MCT1 and MCT4 resulted in a significant increase in MCT transport activity, even in the nominal absence of CO2/HCO3(-). CAIV-mediated augmentation of MCT activity was independent of the CAIV catalytic function, since application of the CA-inhibitor ethoxyzolamide or coexpression of the catalytically inactive mutant CAIV-V165Y did not suppress CAIV-mediated augmentation of MCT transport activity. The interaction required CAIV at the extracellular surface, since injection of CAIV protein into the oocyte cytosol did not augment MCT transport function. The effects of cytosolic CAII (injected as protein) and extracellular CAIV (expressed) on MCT transport activity, were additive. Our results suggest that intra- and extracellular carbonic anhydrases can work in concert to ensure rapid shuttling of metabolites across the cell membrane.

MATERIALS
Product Number
Brand
Product Description

Supelco
Carbonic Anhydrase I from human erythrocytes, Isoelectric focusing marker, pI 6.6
Sigma-Aldrich
Carbonic Anhydrase I from human erythrocytes
Sigma-Aldrich
Carbonic Anhydrase from bovine erythrocytes, non-denaturing PAGE marker
Sigma-Aldrich
Carbonic Anhydrase from bovine erythrocytes, ≥95% (SDS-PAGE), specific activity ≥3,500 W-A units/mg protein, lyophilized powder
Sigma-Aldrich
Carbonic Anhydrase from bovine erythrocytes, lyophilized powder, ≥2,000 W-A units/mg protein
Sigma-Aldrich
Carbonic Anhydrase from bovine erythrocytes, BioReagent, suitable for GFC marker
Sigma-Aldrich
Carbonic Anhydrase from bovine erythrocytes, For use as a marker in SDS-PAGE
Sigma-Aldrich
Carbonic Anhydrase Isozyme II from bovine erythrocytes, Isoelectric focusing marker, pI 5.4
Sigma-Aldrich
Carbonic Anhydrase Isozyme II from bovine erythrocytes, lyophilized powder, ≥2,000 W-A units/mg protein
Sigma-Aldrich
Carbonic Anhydrase Isozyme II human, ≥80%, powder, ≥3,000 W-A units/mg protein
Sigma-Aldrich
Carbonic Anhydrase Isozyme II from bovine erythrocytes, lyophilized powder, ≥3,000 W-A units/mg protein
Sigma-Aldrich
Carbonic Anhydrase II bovine, ≥90% (SDS-PAGE), recombinant, expressed in E. coli, ≥5,000 units/mg protein, buffered aqueous solution
Sigma-Aldrich
Carbonic Anhydrase II human, recombinant, expressed in E. coli, buffered aqueous solution
Sigma-Aldrich
Anti-Monocarboxylate Transporter 4 Antibody, Chemicon®, from rabbit