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LRRC8 amino-termini influence pore properties and gating of volume-regulated VRAC anion channels

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Item Type:Article
Title:LRRC8 amino-termini influence pore properties and gating of volume-regulated VRAC anion channels
Creators Name:Zhou, P. and Polovitskaya, M.M. and Jentsch, T.J.
Abstract:Volume-regulated anion channels (VRACs) are crucial for cell volume regulation and have various roles in physiology and pathology. VRACs were recently discovered to be formed by heteromers of LRRC8 (leucine-rich repeat-containing 8) proteins. However, the structural determinants of VRAC permeation and gating remain largely unknown. We show here that the short stretch preceding the first LRRC8 transmembrane domain determines VRAC conductance, ion permeability and inactivation gating. Substituted cysteine accessibility studies revealed that several of the first 15 LRRC8 residues are functionally important and exposed to a hydrophilic environment. Substituting glutamate 6 with cysteine decreased the amplitudes of swelling-activated ICl,vol currents, strongly increased iodide-over-chloride permeability, and markedly shifted the voltage-dependence of channel inactivation. Importantly, these effects were reversed by 2-sulfonatoethyl-methanethiosulfonate which restores the negative charge at this amino-acid position. Cd2+-mediated blocking of ICl,vol in cysteine variants suggested that the LRRC8 N-termini come close together in the multimeric channel complex and might form part of the pore. We propose a model in which the N termini of the LRRC8 subunits line the cytoplasmic portion of the VRAC pore, possibly by folding back into the ion permeation pathway.
Keywords:Amino Acid Sequence, Cell Size, HCT116 Cells, Ion Transport, Membrane Proteins, Point Mutation, Protein Domains
Source:Journal of Biological Chemistry
ISSN:1083-351X
Publisher:American Society for Biochemistry and Molecular Biology (U.S.A.)
Volume:293
Number:35
Page Range:13440-13451
Date:31 August 2018
Official Publication:https://doi.org/10.1074/jbc.RA118.002853
PubMed:View item in PubMed

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