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Updated: May 20, 2026

Determination of the Relative Cell Surface and Total Expression of Recombinant Ion Channels Using Flow Cytometry
Published on: September 28, 2016
Structural determinants of CaV1.3 L-type calcium channel gating.
Andreas Lieb1, Anja Scharinger, Simone Sartori
1Institute of Pharmacy and Center for Molecular Biosciences, University of Innsbruck, Austria.
The C-terminal modulatory domain (CTM) regulates Ca(v)1.3 channel function. A rat variant (rCa(v)1.3(scg)) lacks a functional CTM, exhibiting distinct gating properties due to specific amino acid differences compared to the functional rat Ca(v)1.3(L) channel.
Area of Science:
- Molecular and Cellular Biology
- Neuroscience
- Biophysics
Background:
- The C-terminal modulatory domain (CTM) critically controls the biophysical characteristics of Ca(v)1.3 L-type Ca(2+) channels.
- Functional CTM is present in human and mouse Ca(v)1.3(L) but absent in a rat Ca(v)1.3(scg) clone.
Purpose of the Study:
- To investigate species-specific differences in Ca(v)1.3 channel function.
- To compare the biophysical properties of rat Ca(v)1.3(L) and rCa(v)1.3(scg) channels.
- To identify the molecular basis for functional variations between rat Ca(v)1.3 variants.
Main Methods:
- Expression of rat Ca(v)1.3(L) and rCa(v)1.3(scg) in tsA-201 cells.
- Electrophysiological recordings to analyze Ca(2+) currents and channel gating.
- Site-directed mutagenesis to pinpoint amino acid residues responsible for functional differences.
Main Results:
- Rat Ca(v)1.3(L) channels displayed properties similar to human and mouse Ca(v)1.3(L), indicating a functional CTM.
- Rat Ca(v)1.3(scg) channels exhibited gating properties resembling human short splice variants lacking a CTM.
- Two specific amino acid substitutions (S244 and A2075) in rCa(v)1.3(scg) were identified as major contributors to altered voltage dependence of activation and Ca(2+)-dependent inactivation.
Conclusions:
- The rat Ca(v)1.3(scg) variant represents a distinct functional isoform lacking a functional CTM, likely due to specific amino acid variations.
- Amino acids S244 and A2075 play significant roles in modulating Ca(v)1.3 channel gating and CTM function.
- This study provides insights into the structural determinants of Ca(v)1.3 channel biophysics and regulation.
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