Coupled control of desensitization and gating by the ligand binding domain of glutamate receptors.
The kinetics of ligand gated ion channels are tuned to permit diverse roles in cellular signaling. To follow high-frequency excitatory synaptic input, postsynaptic AMPA-type glutamate receptors must recover rapidly from desensitization. Chimeras between AMPA and the related kainate receptors demonstrate that the ligand binding domains alone control the lifetime of the desensitized state. Mutation of nonconserved amino acids in the lower lobe (domain 2) of the ligand binding domain conferred slow recovery from desensitization on AMPA receptors, and fast recovery on kainate receptors. Single-channel recordings and a correlation between the rate of deactivation and the rate of recovery across panels of mutant receptors revealed that domain 2 also controls ion channel gating. Our results demonstrate that the same mechanism that ensures fast recovery also sharpens the response of AMPA channels to synaptically released glutamate.
Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany.
Anna L
AL
Carbone
Andrew J R
AJ
Plested
D000596:Amino Acids / Q000235:genetics; D001665:Binding Sites / Q000187:drug effects / Q000235:genetics; D055592:Biophysical Phenomena / Q000187:drug effects* / Q000235:genetics; D002461:Cell Line, Transformed; D004558:Electric Stimulation; D018698:Glutamic Acid / Q000494:pharmacology; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics*; D018408:Patch-Clamp Techniques; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D011499:Protein Processing, Post-Translational; D020836:Protein Structure, Quaternary; D017470:Receptors, Glutamate / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection
D000596:Amino Acids; D008024:Ligands; D017470:Receptors, Glutamate; D018698:Glutamic Acid