Difference between revisions of "Monocarboxylate (Lactate) transporter"

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==Parameters with uncertainty==
 
==Parameters with uncertainty==
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*Monocarboxylate transporter (MCT) 4 is the major monocarboxylate transporter isoform present in white skeletal muscle and is responsible for the efflux of lactic acid produced by glycolysis <ref name="manning_2000">Manning Fox JE ''et. al.'' (2000). ''Characterisation of human monocarboxylate transporter 4 substantiates its role in lactic acid efflux from skeletal muscle''. J Physiol 529(Pt2):285-293</ref>. In animals, L-lactate is constantly produced from pyruvate via the enzyme lactate dehydrogenase (LDH) in a process of fermentation. Therefore in this model the Km value for L-Lactate is only considered. By characterizing MCT4 expressed in Xenopus oocytes the <math>Km_{Lactate_{in}}</math> is defined as <math>28 \pm 4</math> and <math>V_{mf} = 2.5 \pm 0.2</math> <ref name="manning_2000">.
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*Monocarboxylate transporter (MCT) 4 is the major monocarboxylate transporter isoform present in white skeletal muscle and is responsible for the efflux of lactic acid produced by glycolysis <ref name="manning_2000">Manning Fox JE ''et. al.'' (2000). ''Characterisation of human monocarboxylate transporter 4 substantiates its role in lactic acid efflux from skeletal muscle''. J Physiol 529(Pt2):285-293</ref>. In animals, L-lactate is constantly produced from pyruvate via the enzyme lactate dehydrogenase (LDH) in a process of fermentation. Therefore in this model the Km value for L-Lactate is only considered. By characterizing MCT4 expressed in Xenopus oocytes the <math>Km_{Lactate_{in}}</math> is defined as <math>28 \pm 4</math> and <math>V_{mf} = 2.5 \pm 0.2</math> <ref name="manning_2000"></ref>.
  
  

Revision as of 15:56, 2 May 2014


Monocarboxylate transporters,[1] or MCTs, constitute a family of proton-linked plasma membrane transporters that carry molecules having one carboxylate group (monocarboxylates), such as lactate and pyruvate.

Chemical equation

Lactate_{in} \rightleftharpoons Lactate_{out}

Rate equation

Reversible Michaelis-Menten rate law is used

Failed to parse (Cannot store math image on filesystem.): \frac{Vmf \times \frac{[Lactate_{in}]}{Km_{Lactate_{in}}} - Vmr \times \frac{[Lactate_{out}]}{Km_{Lactate_{out}}}}{1 + \frac{[Lactate_{in}]}{Km_{Lactate_{in}}} + \frac{[Lactate_{out}]}{Km_{Lactate_{out}}}}

Parameter values

Parameter Value Units Organism Remarks
V_{mf} 2.5 [2] \text{mM min}^{-1} Human tumor cells
V_{mr} 2.4 [3] \text{mM min}^{-1} Rat liver cells
Km_{Lactate_{in}} 4.5 [3] mM Rat liver cell
Km_{Lactate_{out}} 4.54 [2] mM Human tumor cells

Parameters with uncertainty

  • Monocarboxylate transporter (MCT) 4 is the major monocarboxylate transporter isoform present in white skeletal muscle and is responsible for the efflux of lactic acid produced by glycolysis [2]. In animals, L-lactate is constantly produced from pyruvate via the enzyme lactate dehydrogenase (LDH) in a process of fermentation. Therefore in this model the Km value for L-Lactate is only considered. By characterizing MCT4 expressed in Xenopus oocytes the Km_{Lactate_{in}} is defined as Failed to parse (Cannot store math image on filesystem.): 28 \pm 4 and Failed to parse (Cannot store math image on filesystem.): V_{mf} = 2.5 \pm 0.2 [2].


Parameter Value Units Organism Remarks
V_{mf} Failed to parse (Cannot store math image on filesystem.): 2.5 \pm 0.2 \text{mM min}^{-1} Human tumor cells
V_{mr} 2.4 [3] \text{mM min}^{-1} Rat liver cells
Km_{Lactate_{in}} Failed to parse (Cannot store math image on filesystem.): 28 \pm 4 (6) mM Rat liver cell
Km_{Lactate_{out}} 4.54 [2] mM Human tumor cells

References

  1. ↑ Halestrap AP, Meredith D (2004). The SLC16 gene family-from monocarboxylate transporters (MCTs) to aromatic amino acid transporters and beyond. Pflugers Arch. 447 (5): 619–28 (doi)
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Manning Fox JE et. al. (2000). Characterisation of human monocarboxylate transporter 4 substantiates its role in lactic acid efflux from skeletal muscle. J Physiol 529(Pt2):285-293
  3. ↑ 3.0 3.1 3.2 Jackson VN, Halestrap AP (1996) The kinetics, substrate, and inhibitor specificity of the monocarboxylate (lactate) transporter of rat liver cells determined using the fluorescent intracellular pH indicator, 2’,7’-bis(carboxyethyl)-5(6)-carboxyfluorescein. J Biol Chem 271:861–868
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