Monocarboxylate (Lactate) transporter
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.
Contents
Chemical equation
![Lactate_{in} \rightleftharpoons Lactate_{out}](/wiki/images/math/9/4/7/9473e479aa23c3e2aa5b6b08d60ad0d7.png)
Rate equation
Reversible Michaelis-Menten rate law is used
![\frac{V_{mf} \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}}}}](/wiki/images/math/9/7/f/97f35c7a18828761f166888b13a2c645.png)
Modified rate law to take Thermodynamic constraint into consideration
![\frac{V_{mf} \frac{[Lactate_{in}]}{Km_{Lactate_{in}}} \left(1 - \frac{[Lactate_{out}]}{K_{eq}[Lactate_{in}] } \right)}{1 + \frac{[Lactate_{in}]}{Km_{Lactate_{in}}} + \frac{[Lactate_{out}]}{Km_{Lactate_{out}}}}](/wiki/images/math/5/5/e/55ea56557248babfe67ad27eaf2220f9.png)
Parameter values
Parameter | Value | Units | Organism | Remarks |
---|---|---|---|---|
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2.5 [2] | ![]() |
Human tumor cells | |
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2.4 [3] | ![]() |
Rat liver cells | |
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4.5 [3] | mM | Rat liver cell | |
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4.54 [2] | mM | Human tumor cells |
Parameters with uncertainty
- Among different isoforms the MCT1 in Tumour cells are considered in this model. The
is defined as
and
[2] with 6 experiments.
- In the legend of Table-1 of [3] it states Km and Vmax values for monocarboxylate transport into mouse Ehrlich Lettre ́ tumor cells were taken in to consideration. Therefore we consider these values to be for
and
. Here the values are given in
with 7 experiments. Calculating Std. Dev. from S.E gives,
for
and
for
.
Parameter | Value | Units | Organism | Remarks |
---|---|---|---|---|
![]() |
![]() |
![]() |
Human tumor cells | |
![]() |
![]() |
![]() |
Human Tumor cell | |
![]() |
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mM | Human tumour cell | |
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mM | Human tumor cells |
Equilibrium constant
Alternative: The value of the transporters are reported to be 1.00.[4][5] As the
is directly related to
values of substrate and product, the uncertainty would also be dependent. The highest uncertainty is mentioned for
which is
of the actual value. The same percentage of error is assumed for
;
References
- ↑ 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)
- ↑ 2.0 2.1 2.2 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
- ↑ 3.0 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
- ↑ Ettore Murabito (2011), Application of Differential Metabolic Control Analysis to Identify New Targets in Cancer Treatment, (PhD Thesis), University of Manchester
- ↑ F. Achcar, E.J. Kerkhoven, B.M. Bakker, M.P. Barrett, R. Breitling (2012), Dynamic modelling under uncertainty: the case of Trypanosoma brucei energy metabolism, PLoS Comput Biol, 8, p. e1002352