Dopamine transporters depolarize neurons by a channel mechanism.
Neurotransmitter transporters generate larger currents than expected if one assumes fixed stoichiometry models. It remains controversial, however, whether these depolarizing currents arise from high density and rapid turnover rates of a classical transporter, or whether transporters exhibit bona fide channel behavior. Although heterologously expressed transporters show single-channel behavior and noise analysis in native cells strongly suggests channel behavior, no directly observed single-channel events associated with transporters have been reported thus far in native cells. We describe single-channel events arising directly from the Caenorhabditis elegans dopamine transporter (DAT-1) as evidenced by DA-induced channel activity blocked by a high-affinity DAT-1 inhibitor, increased channel activity in neurons that overexpress DAT-1, and loss of channels in dat-1 knockout neurons. Our data indicate that authentic transporter channels underlie depolarizing whole-cell currents. Thus, DA transporters not only transport DA but also exhibit a channel mode of conduction that directly modulates membrane potential and neuronal function.
Carvelli
Lucia
L
Department of Pharmacology and Center of Neuroscience, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, USA. lucia.carvelli@vanderbilt.edu
McDonald
Paul W
PW
Blakely
Randy D
RD
DeFelice
Louis J
LJ
D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D018509:DNA, Helminth / Q000235:genetics; D004298:Dopamine / Q000378:metabolism; D050483:Dopamine Plasma Membrane Transport Proteins; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008564:Membrane Potentials; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D018509:DNA, Helminth; D050483:Dopamine Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D004298:Dopamine