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Pore-lining residues identified by single channel SCAM studies in Cx46 hemichannels
J Kronengold1, E B Trexler, F F Bukauskas
1Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Cell Communication & Adhesion
|December 19, 2003
Summary
This study used the substituted cysteine accessibility method to map the pore of Cx46 hemichannels. Researchers identified key amino acid residues, D51 and L35, that line the channel
Area of Science:
- Molecular biology
- Biophysics
- Ion channel research
Background:
- Connexins form channels crucial for intercellular communication.
- Cx46 hemichannels are important for understanding channel structure and function.
- The aqueous pore is critical for selective ion and molecule transport.
Purpose of the Study:
- To identify amino acid residues lining the aqueous pore of single Cx46 hemichannels.
- To determine the contribution of specific residues to hemichannel properties.
- To map the boundaries of the pore-lining region.
Main Methods:
- Substituted cysteine accessibility method (SCAM).
- Application of sulfhydryl-specific methanethiosulfonate (MTS) reagents.
- Analysis of single open hemichannel properties and reactivity.
- Site-directed mutagenesis of connexin 46 (Cx46).
Main Results:
- Identified a 17-amino acid stretch (D51 through L35) in E1 and TM1 segments lining the Cx46 hemichannel pore.
- D51 and L35 define the extracellular and intracellular limits of the pore, respectively.
- Side chain valence significantly influences single channel properties.
- MTS reagent modification effects varied with reagent size and subunit number.
Conclusions:
- The pore-lining region of Cx46 hemichannels involves specific residues in TM1 and E1 segments.
- Residue D51 and L35 are critical for defining the pore's extracellular and intracellular boundaries.
- Channel properties are modulated by the chemical nature and accessibility of pore-lining residues.
