Abstract
Recent studies have indicated that the Shaker potassium channel regulates sleep in Drosophila. The Drosophila quiver (qvr) gene encodes a novel potassium channel subunit that modulates the Shaker potassium channel. The Qvr peptide contains a signal sequence for extracellular localization and may regulate a unique feature of the Shaker I(A) current that confers special neuronal excitability patterns. Thus, studies of the Shaker channel properties in the qvr mutant background should provide an opportunity to uncover a new form of physiologic modulation of potassium channels. We have begun to investigate the impact of qvr protein on the Shaker channel properties and its implications in synaptic function in vivo. We studied synaptic transmission at the larval neuromuscular junction and characterized the transient potassium current I(A) in larval muscles. We identified two different functional states of I(A) in qvr larval muscles, as reflected by two distinct components, I(AF) and I(AS), differing in their kinetics of recovery from inactivation and sensitivity to a K(+) channel blocker. Correspondingly, qvr mutant larvae exhibit multiple synaptic discharges following individual nerve stimuli during repetitive activity.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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4-Aminopyridine / pharmacology
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Animals
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Drosophila Proteins / antagonists & inhibitors
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Drosophila Proteins / genetics
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Drosophila Proteins / metabolism*
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Drosophila Proteins / physiology*
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Drosophila melanogaster
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Excitatory Postsynaptic Potentials / drug effects
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Excitatory Postsynaptic Potentials / genetics
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Extracellular Space / genetics
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Extracellular Space / metabolism
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Extracellular Space / physiology
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Kinetics
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Larva / genetics
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Larva / metabolism
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Membrane Proteins
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Mutation / genetics
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Neuromuscular Junction / genetics
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Neuromuscular Junction / metabolism*
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Neuropeptides / genetics
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Neuropeptides / physiology*
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Organ Culture Techniques
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Potassium Channel Blockers / metabolism
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Potassium Channel Blockers / pharmacology
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Potassium Channels / genetics
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Potassium Channels / metabolism
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Potassium Channels / physiology*
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Protein Subunits / genetics
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Protein Subunits / metabolism
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Protein Subunits / physiology*
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Recovery of Function / drug effects
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Recovery of Function / genetics
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Shaker Superfamily of Potassium Channels / antagonists & inhibitors
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Shaker Superfamily of Potassium Channels / genetics
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Shaker Superfamily of Potassium Channels / metabolism*
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Synaptic Transmission / genetics
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Synaptic Transmission / physiology
Substances
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Drosophila Proteins
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Membrane Proteins
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Neuropeptides
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Potassium Channel Blockers
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Potassium Channels
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Protein Subunits
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Qvr protein, Drosophila
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Sh protein, Drosophila
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Shaker Superfamily of Potassium Channels
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4-Aminopyridine