Distinct modes of N-terminal remodeling through a conserved inhibitor pocket in connexin-46/50
Abstract
Selective pharmacological control of gap junction communication remains challenging because existing small-molecule connexin inhibitors act across multiple isoforms. The structural basis of this broad activity remains incompletely understood. Here, we used single-particle cryo-electron microscopy to examine native connexin-46/50 gap junction channels treated with two commonly used and chemically distinct inhibitors, 2-aminoethoxydiphenyl borate (2-APB) and carbenoxolone (CBX). Both treatments perturb the hydrophobic N-terminal (NT)-docking groove, but produce distinct conformational ensembles. 2-APB yields ordered destabilized-open and gated NT states resembling conformations observed during physiological pH- and Ca2+-dependent gating, with ligand- and lipid-associated densities accompanying the gated state. In contrast, CBX-compatible density occupies the same groove and is associated with loss of an ordered NT conformation, consistent with steric competition and altered physicochemical complementarity at the NT-docking site. Comparison with inhibitor-treated connexin-32 and connexin-36 structures identifies this region as a structurally conserved, pharmacologically sensitive pocket. These findings reveal how chemically diverse inhibitors perturb a conserved element of the native gating machinery while producing divergent NT-gating ensembles, providing a structural rationale for broad cross-isoform activity and identifying sequence-variable pocket margins that may support more selective modulation.
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BibTeX
@misc{jarodsky2026distinct,
title = {{Distinct modes of N-terminal remodeling through a conserved inhibitor pocket in connexin-46/50}},
author = {Joshua M. Jarodsky and Janette B. Myers and Steve L. Reichow},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.26.762086},
url = {https://www.biorxiv.org/content/10.64898/2026.10.26.762086v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Distinct modes of N-terminal remodeling through a conserved inhibitor pocket in connexin-46/50
AU - Joshua M. Jarodsky
AU - Janette B. Myers
AU - Steve L. Reichow
PY - 2026
DA - 2026/10/26
PB - bioRxiv
DO - 10.64898/2026.10.26.762086
UR - https://www.biorxiv.org/content/10.64898/2026.10.26.762086v1
AB - Selective pharmacological control of gap junction communication remains challenging because existing small-molecule connexin inhibitors act across multiple isoforms. The structural basis of this broad activity remains incompletely understood. Here, we used single-particle cryo-electron microscopy to examine native connexin-46/50 gap junction channels treated with two commonly used and chemically distinct inhibitors, 2-aminoethoxydiphenyl borate (2-APB) and carbenoxolone (CBX). Both treatments perturb the hydrophobic N-terminal (NT)-docking groove, but produce distinct conformational ensembles. 2-APB yields ordered destabilized-open and gated NT states resembling conformations observed during physiological pH- and Ca2+-dependent gating, with ligand- and lipid-associated densities accompanying the gated state. In contrast, CBX-compatible density occupies the same groove and is associated with loss of an ordered NT conformation, consistent with steric competition and altered physicochemical complementarity at the NT-docking site. Comparison with inhibitor-treated connexin-32 and connexin-36 structures identifies this region as a structurally conserved, pharmacologically sensitive pocket. These findings reveal how chemically diverse inhibitors perturb a conserved element of the native gating machinery while producing divergent NT-gating ensembles, providing a structural rationale for broad cross-isoform activity and identifying sequence-variable pocket margins that may support more selective modulation.
SN - 2692-8205
ER -