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Calcium-activated potassium channels expressed from cloned complementary DNAs.
J P Adelman1, K Z Shen, M P Kavanaugh
1Vollum Institute, Oregon Health Sciences University, Portland 97201.
Neuron
|August 1, 1992
Summary
Alternative splicing of Drosophila melanogaster slo locus cDNAs generates a diverse family of calcium-activated potassium channels. These channels exhibit varied functional properties, influencing cellular excitability.
Area of Science:
- Molecular Biology
- Neuroscience
- Ion Channel Physiology
Background:
- Calcium-activated potassium channels are crucial for regulating cellular excitability.
- The Drosophila melanogaster slo locus is a key genetic determinant of these channels.
Purpose of the Study:
- To investigate the molecular basis of functional diversity in calcium-activated potassium channels.
- To determine if alternative splicing contributes to the variety of channel properties.
Main Methods:
- In vitro RNA transcription and Xenopus oocyte expression of cDNAs from the Drosophila slo locus.
- Electrophysiological recordings (inside-out patch clamp) to characterize channel activity.
- Analysis of single-channel conductance, open time, and calcium/voltage sensitivity.
Main Results:
- Multiple cDNAs encoding ~1200 amino acid proteins were identified, differing in intracellular regions.
- Expressed channels are calcium-activated, with activity dependent on calcium concentration and membrane potential.
- Distinct amino acid substitutions correlated with significant differences in mean channel open times.
Conclusions:
- Alternative splicing of the Drosophila slo locus generates a large family of functionally distinct calcium-activated potassium channels.
- This molecular diversification provides a mechanism for fine-tuning cellular excitability in response to physiological stimuli.