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Updated: Aug 15, 2026

Crystal Structure of the N-terminal Domain of Ryanodine Receptor from Plutella xylostella
Published on: November 30, 2018
Probing luminal negative charge in the type 3 ryanodine receptor
Nicholas Pugh1, Fiona C Mead-Savery, W John Coadwell
1The Laboratory of Functional Immunogenetics, The Babraham Institute, Cambridge CB2 4AT, UK.
Neomycin blocks potassium current in the type 3 ryanodine receptor (RyR3) from the luminal side. This polycation exhibits higher affinity for RyR3 than RyR2, suggesting altered charge density in the RyR3 pore mouth.
Area of Science:
- Ion channel pharmacology
- Molecular physiology
- Biophysics
Background:
- Ryanodine receptors (RyRs) are critical calcium release channels.
- Type 3 ryanodine receptor (RyR3) function is less understood than RyR1 and RyR2.
- Polycations like neomycin can block ion channels.
Purpose of the Study:
- To investigate the blocking effect of neomycin on potassium currents through RyR3.
- To probe the luminal pore mouth of RyR3 for negatively charged residues.
- To compare neomycin's interaction with RyR3 to its known interaction with RyR2.
Main Methods:
- Electrophysiological recordings of single RyR3 channels.
- Application of neomycin to the luminal side of the channel.
- Concentration- and voltage-clamp analysis of neomycin block.
Main Results:
- Luminal neomycin induced a concentration- and voltage-dependent partial block of RyR3.
- Neomycin reduced RyR3 conductance to a subconductance state.
- Neomycin demonstrated a higher affinity for RyR3 compared to RyR2.
Conclusions:
- Neomycin acts as an open channel blocker on RyR3 from the luminal side.
- The pore mouth of RyR3 likely contains negatively charged residues interacting with neomycin.
- Differences in neomycin affinity suggest altered charge density in the RyR3 pore compared to RyR2.
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