Energetic Contributions to Channel Gating of Residues in the Muscle Nicotinic Receptor β1 Subunit

Gustav Akk, Megan Eaton, Ping Li, Steven Zheng, Joshua Lo, Joe Henry Steinbach

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

In the pentameric ligand-gated ion channel family, transmitter binds in the extracellular domain and conformational changes result in channel opening in the transmembrane domain. In the muscle nicotinic receptor and other heteromeric members of the family one subunit does not contribute to the canonical agonist binding site for transmitter. A fundamental question is whether conformational changes occur in this subunit. We used records of single channel activity and rate-equilibrium free energy relationships to examine the β1 (non-ACh-binding) subunit of the muscle nicotinic receptor. Mutations to residues in the extracellular domain have minimal effects on the gating equilibrium constant. Positions in the channel lining (M2 transmembrane) domain contribute strongly and relatively late during gating. Positions thought to be important in other subunits in coupling the transmitter-binding to the channel domains have minimal effects on gating. We conclude that the conformational changes involved in channel gating propagate from the binding-site to the channel in the ACh-binding subunits and subsequently spread to the non-binding subunit.

Original languageEnglish
Article numbere78539
JournalPloS one
Volume8
Issue number10
DOIs
StatePublished - Oct 23 2013

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