| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Biophysical Journal 70: 733-742 (1996)
© 1996 the Biophysical Society
Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA.
ABSTRACT
The glutamate-activated current in photoreceptors has been attributed both to a sodium/glutamate transporter and to a glutamate-activated chloride channel. We have further studied the glutamate-activated current in single, isolated photoreceptors from the tiger salamander using noise analysis on whole-cell patch-clamp recordings. In cones, the current is generated by chloride channels with a single-channel conductance of 0.7 pS and an open lifetime of 2.4 ms. The number of channels per cell is in the range of 10,000-20,000. Activation of the channels requires the presence of both glutamate and sodium. The single-channel conductance and the open lifetime of the channel are independent of the external concentration of glutamate and sodium. External glutamate and sodium affect only the opening rate of the channels. D,L-Threo-3-hydroxyaspartate (THA), a glutamate-transport blocker, is shown to be a partial agonist for the channel. The single-channel conductance is the same regardless of whether glutamate or THA is the ligand, but the open lifetime of the channel is only 0.8 ms with THA as ligand. The glutamate-activated current in rods has a similar single-channel conductance (0.74 pS) and open lifetime (3 ms). We propose a kinetic model, consistent with these results, to explain how a transporter can simultaneously act both as a sodium/glutamate-gated chloride channel and a glutamate/sodium cotransporter.
This article has been cited by other articles:
 |
|
 |
|
  D. Torres-Salazar and C. Fahlke Intersubunit interactions in EAAT4 glutamate transporters. J. Neurosci., July 12, 2006; 26(28): 7513 - 7522. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Melzer, D. Torres-Salazar, and C. Fahlke A dynamic switch between inhibitory and excitatory currents in a neuronal glutamate transporter PNAS, December 27, 2005; 102(52): 19214 - 19218. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. W. Schwartz, G. Novarino, D. W. Piston, and L. J. DeFelice Substrate Binding Stoichiometry and Kinetics of the Norepinephrine Transporter J. Biol. Chem., May 13, 2005; 280(19): 19177 - 19184. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Gendreau, S. Voswinkel, D. Torres-Salazar, N. Lang, H. Heidtmann, S. Detro-Dassen, G. Schmalzing, P. Hidalgo, and C. Fahlke A Trimeric Quaternary Structure Is Conserved in Bacterial and Human Glutamate Transporters J. Biol. Chem., September 17, 2004; 279(38): 39505 - 39512. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Melzer, A. Biela, and C. Fahlke Glutamate Modifies Ion Conduction and Voltage-dependent Gating of Excitatory Amino Acid Transporter-associated Anion Channels J. Biol. Chem., December 12, 2003; 278(50): 50112 - 50119. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. B. Thoreson, E. J. Bryson, and K. Rabl Reciprocal Interactions Between Calcium and Chloride in Rod Photoreceptors J Neurophysiol, September 1, 2003; 90(3): 1747 - 1753. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. J. Palmer, H. Taschenberger, C. Hull, L. Tremere, and H. von Gersdorff Synaptic Activation of Presynaptic Glutamate Transporter Currents in Nerve Terminals J. Neurosci., June 15, 2003; 23(12): 4831 - 4841. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. E. Bergles, A. V. Tzingounis, and C. E. Jahr Comparison of Coupled and Uncoupled Currents during Glutamate Uptake by GLT-1 Transporters J. Neurosci., December 1, 2002; 22(23): 10153 - 10162. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. S. Otis and M. P. Kavanaugh Isolation of Current Components and Partial Reaction Cycles in the Glial Glutamate Transporter EAAT2 J. Neurosci., April 15, 2000; 20(8): 2749 - 2757. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Galli, L. D. Jayanthi, I. S. Ramsey, J. W. Miller, R. T. Fremeau Jr, and L. J. DeFelice L-Proline and L-Pipecolate Induce Enkephalin-Sensitive Currents in Human Embryonic Kidney 293 Cells Transfected with the High-Affinity Mammalian Brain L-Proline Transporter J. Neurosci., August 1, 1999; 19(15): 6290 - 6297. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. N. Petty and M. T. Lucero Characterization of a Na+-Dependent Betaine Transporter With Cl- Channel Properties in Squid Motor Neurons J Neurophysiol, April 1, 1999; 81(4): 1567 - 1574. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. J. Chrispeels, N. M. Crawford, and J. I. Schroeder Proteins for Transport of Water and Mineral Nutrients across the Membranes of Plant Cells PLANT CELL, April 1, 1999; 11(4): 661 - 676. [Full Text]
|
|
|
|
|
|
M. P. Kavanaugh Neurotransmitter transport: Models in flux PNAS, October 27, 1998; 95(22): 12737 - 12738. [Full Text] [PDF]
|
|
|
|
|
|
A. Galli, R. D. Blakely, and L. J. DeFelice Patch-clamp and amperometric recordings from norepinephrine transporters: Channel activity and voltage-dependent uptake PNAS, October 27, 1998; 95(22): 13260 - 13265. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. PALACIN, R. ESTEVEZ, J. BERTRAN, and A. ZORZANO Molecular Biology of Mammalian Plasma Membrane Amino Acid Transporters Physiol Rev, October 1, 1998; 78(4): 969 - 1054. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. I. Wadiche and M. P. Kavanaugh Macroscopic and Microscopic Properties of a Cloned Glutamate Transporter/Chloride Channel J. Neurosci., October 1, 1998; 18(19): 7650 - 7661. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Gaal, B. Roska, S. A. Picaud, S. M. Wu, R. Marc, and F. S. Werblin Postsynaptic Response Kinetics Are Controlled by a Glutamate Transporter at Cone Photoreceptors J Neurophysiol, January 1, 1998; 79(1): 190 - 196. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Lebrun, M. Sakaitani, K. Shimamoto, Y. Yasuda-Kamatani, and T. Nakajima New beta -Hydroxyaspartate Derivatives Are Competitive Blockers for the Bovine Glutamate/Aspartate Transporter J. Biol. Chem., August 15, 1997; 272(33): 20336 - 20339. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Galli, C.I. Petersen, M. deBlaquiere, R.D. Blakely, and L.J. DeFelice Drosophila Serotonin Transporters Have Voltage-Dependent Uptake Coupled to a Serotonin-Gated Ion Channel J. Neurosci., May 15, 1997; 17(10): 3401 - 3411. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. S. Sonders, S.-J. Zhu, N. R. Zahniser, M. P. Kavanaugh, and S. G. Amara Multiple Ionic Conductances of the Human Dopamine Transporter: The Actions of Dopamine and Psychostimulants J. Neurosci., February 1, 1997; 17(3): 960 - 974. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Zerangue and M. P. Kavanaugh ASCT-1 Is a Neutral Amino Acid Exchanger with Chloride Channel Activity J. Biol. Chem., November 8, 1996; 271(45): 27991 - 27994. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
