The Journal of Neuroscience, April 4, 2007, 27(14):3780-3789; doi:10.1523/JNEUROSCI.4185-06.2007
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Cellular/Molecular
Electrophysiological Properties of AMPA Receptors Are Differentially Modulated Depending on the Associated Member of the TARP Family
Sabine Kott,
Markus Werner,
Christoph Körber, and
Michael Hollmann
Department of Biochemistry I, Receptor Biochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
Correspondence should be addressed to Dr. Michael Hollmann, Department of Biochemistry I, Receptor Biochemistry, Building NC, Room 6/171, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum, Germany. Email: michael.hollmann{at}rub.de
The family of AMPA receptors is encoded by four genes that are differentially spliced to result in the flip or flop versions of the four subunits GluR1 to GluR4. GluR2 is further modified at the so-called Q/R site by posttranscriptional RNA editing. Delivery of AMPA receptors to the plasma membrane and synaptic trafficking are controlled by transmembrane AMPA receptor regulatory proteins (TARPs). Additionally, TARPs influence essential electrophysiological properties of AMPA receptor channels such as desensitization and agonist efficacies. Here, we compare the influence of all known TARPs (
2,
3,
4, and
8) on agonist-induced currents of the four AMPA receptor subunits, including flip and flop splice variants and editing variants. We show that, although agonist-induced currents of all homomeric AMPA receptor subunits as well as all heteromeric combinations tested are significantly potentiated when coexpressed with members of the TARP family in Xenopus laevis oocytes, the extent of TARP-mediated increase in agonist-induced responses is highly dependent on both the AMPA receptor subunit and the coexpressed TARP. Moreover, we demonstrate that the splice variant of the AMPA receptor plays a key role in determining the modulation of electrophysiological properties by associated TARPs. We furthermore present evidence that individual TARPAMPA receptor interactions control the degree of desensitization of AMPA receptors. Consequently, because of their subunit-specific impact on the electrophysiological properties, TARPs play a major role as modulatory subunits of AMPA receptors and thus contribute to the functional diversity of AMPA receptors encountered in the CNS.
Key words: glutamate receptor; stargazin; TARP; trafficking; voltage clamp; AMPA receptor
Received Sept. 25, 2006;
revised Feb. 27, 2007;
accepted Feb. 28, 2007.
Correspondence should be addressed to Dr. Michael Hollmann, Department of Biochemistry I, Receptor Biochemistry, Building NC, Room 6/171, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum, Germany. Email: michael.hollmann{at}rub.de
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K. Menuz, J. L. O'Brien, S. Karmizadegan, D. S. Bredt, and R. A. Nicoll
TARP Redundancy Is Critical for Maintaining AMPA Receptor Function
J. Neurosci.,
August 27, 2008;
28(35):
8740 - 8746.
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