Potassium channel subfamily K member 9 is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
that in humans is encoded by the ''KCNK9''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
.
This gene encodes K
2P9.1, one of the members of the superfamily of potassium channel proteins containing two pore-forming P domains. This open channel is highly expressed in the cerebellum. It is inhibited by extracellular acidification and
arachidonic acid, and strongly inhibited by phorbol 12-myristate 13-acetate.
Phorbol 12-myristate 13-acetate is also known as
12-''O''-tetradecanoylphorbol-13-acetate (TPA). TASK channels are additionally inhibited by hormones and transmitters that signal through GqPCRs. The resulting cellular depolarization is thought to regulate processes such as motor control and
aldosterone secretion. Despite early controversy about the exact mechanism underlying this inhibition, the current view is that
Diacyl-glycerol, produced by the breakdown of
Phosphatidylinositol-4,5-bis-phosphate by
Phospholipase CĪ² causes channel closure.
Expression
The KCNK9 gene is expressed as an ion channel more commonly known as TASK 3. This channel has a varied pattern of expression. TASK 3 is coexpressed with TASK 1 (
KCNK3
Potassium channel subfamily K member 3 is a protein that in humans is encoded by the ''KCNK3'' gene.
This gene encodes K2P3.1, one of the members of the superfamily of potassium channel proteins containing two pore-forming P domains. K2P3.1 is an ...
) in the cerebellar granule cells, locus coeruleus, motor neurons, pontine nuclei, some cells in the neocortex, habenula, olfactory bulb granule cells, and cells in the external plexiform layer of the olfactory bulb. TASK-3 channels are also expressed in the hippocampus; both on pyramidal cells and interneurons. It is thought that these channels may form heterodimers where their expressions co-localise.
Function
Mice in which the TASK-3 gene has been deleted have reduced sensitivity to inhalation anaesthetics, exaggerated nocturnal activity and cognitive deficits as well as significantly increased appetite and weight gain.
A role for TASK-3 channels in neuronal network oscillations has also been described: TASK-3 knockout mice lack the atropine-sensitive halothane-induced theta oscillation (4ā7 Hz) from the hippocampus and are unable to maintain theta oscillations during rapid eye movement (REM) sleep.
Interactive pathway map
See also
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Tandem pore domain potassium channel
The two-pore-domain or tandem pore domain potassium channels are a family of 15 members that form what is known as leak channels which possess Goldman-Hodgkin-Katz (open) rectification. These channels are regulated by several mechanisms including ...
References
Further reading
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External links
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{{Ion channels, g3
Ion channels