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Updated: Jul 17, 2026

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells
Published on: October 1, 2010
Structural determinants of ion flow through recombinant glutamate receptor channels
T A Verdoorn1, N Burnashev, H Monyer
1Max-Planck-Institut für medizinische Forschung, Abteilung Zellphysiologie, Heidelberg, Federal Republic of Germany.
Abstract:
Functional glutamate receptor (GluRs) were transiently expressed in cultured mammalian cells from cloned complementary DNAs encoding GluR-A, -B, -C, or -D polypeptides. The steady-state current-voltage (I-V) relations of glutamate- and kainate-induced currents through homomeric channels fell into two classes: channels composed of either the GluR-A, -C, and -D subunits showed doubly rectifying I-V curves, and channels composed of the GluR-B subunits displayed simple outward rectification. The presence of GluR-B subunits in heteromeric GluRs determined the I-V behavior of the resulting channels. Site-directed mutagenesis identified a single amino acid difference (glutamine to arginine) in the putative transmembrane segment TM2 responsible for subunit-specific I-V relationships. The properties of heteromeric wild-type and mutant GluRs revealed that the dominance of GluR-B is due to the arginine residue in the TM2 region.
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