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Full-Text Articles in Medicine and Health Sciences
Asct-1 Is A Neutral Amino Acid Exchanger With Chloride Channel Activity, Noa Zerangue, Michael Kavanaugh
Asct-1 Is A Neutral Amino Acid Exchanger With Chloride Channel Activity, Noa Zerangue, Michael Kavanaugh
Biomedical and Pharmaceutical Sciences Faculty Publications
The ubiquitous transport activity known as system ASC is characterized by a preference for small neutral amino acids including alanine, serine, and cysteine. ASCT-1 and ASCT-2, recently cloned transporters exhibiting system ASC-like selectivity, are members of a major amino acid transporter family that includes a number of glutamate transporters. Here we show that ASCT1 functions as an electroneutral exchanger that mediates negligible net amino acid flux. The electrical currents previously shown to be associated with ASCT1-mediated transport result from activation of a thermodynamically uncoupled chloride conductance with permeation properties similar to those described for the glutamate transporter subfamily. Like glutamate …
Kinetics And Stoichiometry Of A Proton/Myo-Inositol Cotransporter, Elizabeth M. Klamo, Mark E. Drew, Scott M. Landfear, Michael Kavanaugh
Kinetics And Stoichiometry Of A Proton/Myo-Inositol Cotransporter, Elizabeth M. Klamo, Mark E. Drew, Scott M. Landfear, Michael Kavanaugh
Biomedical and Pharmaceutical Sciences Faculty Publications
Voltage clamp recording was used to measure steady-state and presteady-state currents mediated by a myo-inositol transporter cloned from Leishmania donovani and expressed in Xenopus oocytes. Application of myo-inositol resulted in inward currents, which did not require external sodium and which were increased by increasing the extracellular proton concentration and by membrane hyperpolarization. Alkalinization of the extracellular space occurred concomitantly with myo-inositol influx. Correlation of membrane currents with radiolabeled myo-inositol flux revealed that one positive charge is translocated with each molecule of myo-inositol, consistent with cotransport of one proton. The transport concentration dependence on both species …