Putative Pore-lining Residues and Intracellular Magnesium Influence Connexin50 Unitary Gap Junction Channel Conductance

Author

Swathy Sudhakar, The University of Western OntarioFollow

Degree

Master of Science

Program

Physiology and Pharmacology

Supervisor

Dr. Donglin Bai

Abstract

Gap junction channels (GJs) are oligomers of connexins forming channels linking neighbouring cells. GJs formed by different connexins show distinct unitary channel conductance (γ_j), transjunctional-voltage dependent gating (V_j-gating) properties, and magnesium modulation. We investigate here how pore-lining residues may influence these GJ properties. We mutated putative pore-lining residues in Cx50 GJ (G8E/G46E/V53E individually or in combination) to investigate γ_j, V_j-gating, and magnesium modulation. GJs formed by combination mutants (G8E-G46E, G46E-V53E, and G8E-G46E-V53E) were functional and showed a significantly increased γ_j with little change in V_j-gating, while G8E-V53E mutants failed to form functional GJs. The γ_js of the mutant GJs were reduced up to 30% by inclusion of magnesium in intracellular solution. Studying the individual mutations revealed that magnesium-dependent reduction of γ_j are due to one or combinations of V53E and/or G46E. Increasing negatively charged glutamate residues at 53^rd and/or 46^th positions of Cx50 increased magnesium-sensitive ion permeation.

Recommended Citation

Sudhakar, Swathy, "Putative Pore-lining Residues and Intracellular Magnesium Influence Connexin50 Unitary Gap Junction Channel Conductance" (2016). Electronic Thesis and Dissertation Repository. 3824.
https://ir.lib.uwo.ca/etd/3824