Intracellular accumulation of l-Arg, kinetics of transport, and potassium leak conductance in oocytes from Xenopus laevis expressing hCAT-1, hCAT-2A, and hCAT-2B
| Autor: | Alexander Rotmann, Ellen I. Closs, Jana F. Liewald, Hermann Nawrath |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Patch-Clamp Techniques
Voltage clamp Xenopus Biophysics Arginine Biochemistry Membrane Potentials Xenopus laevis Voltage dependence hCAT Animals Patch clamp Cationic Amino Acid Transporter 2 y+ Cationic Amino Acid Transporter 1 Membrane potential biology Chemistry Biological Transport Transporter Cell Biology biology.organism_classification Vmax KM Kinetics Conductance Oocytes Potassium Amino Acid Transport Systems Basic Efflux Steady state (chemistry) Intracellular |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Biomembranes. 1660(1-2):138-143 |
| ISSN: | 0005-2736 |
| DOI: | 10.1016/j.bbamem.2003.11.009 |
| Popis: | Cationic amino acid transporters play an important role in the intracellular supply of l-Arg and the generation of nitric oxide. Since the transport of l-Arg is voltage-dependent, we aimed at determining the intracellular l-Arg concentration and describing the transport of l-Arg in terms of Michaelis–Menten kinetics, taking into account membrane voltage. The human isoforms of the cationic amino acid transporters, hCAT-1, hCAT-2A, and hCAT-2B, were expressed in oocytes from Xenopus laevis and studied with the voltage clamp technique and in tracer experiments. We found that l-Arg was concentrated intracellularly by all hCAT isoforms and that influx and efflux, in the steady state of exchange, were nearly mirror images. Conductance measurements at symmetric concentrations of l-Arg (inside/outside) allowed us to determine KM and Vmax. The empty transporter of hCAT-2B featured an unexpected potassium conductance, which was inhibited by l-Arg. |
| Databáze: | OpenAIRE |
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